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ДНІПРОПЕТРОВСЬКА МЕДИЧНА АКАДЕМІЯ DNIPROPETROVSK MEDICAL ACADEMY КАФЕДРА ГІСТОЛОГІЇ DEPARTMENT OF HISTOLOGY Glossary of Histology (with microphotograph index) Igor V. Tverdokhleb, Ph.D. (Department of Histology, Dnipropetrovsk Medical Academy) Дніпропетровськ - 2013 Dnipropetrovsk - 2013 2 A • Photomicrograph of breast adenocarcinoma adenohypophysis anterior lobe of the pituitary; composed of glandular secretory tissue adipocyte large cell (up to 200 um in diameter) with only a thin rim of cytoplasm due to the presence of a large flat droplet; TEM shows an external lamina; stores large lipid vacuoles • Photomicrograph of adipocyte • Photomicrograph of adipocyte A band a region containing the full length of the myosin filaments and also parts of actin filaments; located in the sarcomere of skeletal muscle; see also H band • Photomicrograph of A band absorptive cell Cell that is efficient in absorbing substances from the lumen via apical cytoplasmic processes (microvilli or stereocilia) • Photomicrograph of absorptive cell adipose tissue a grouping of adipocytes • Photomicrograph of adipose • Photomicrograph of adipose acidophil cell of the adenohypophysis which stains pink red; i.e. somatotropes and mammatropes • Photomicrograph of acidophil adrenocorticolipotrope cell of the adenohypophysis which produces ACTH and LPH adventitia connective tissue with high content of adipose, nerves, and blood vessels acinar cell a cell of an acinus unit • Photomicrograph of breast adenocarcinoma afferent arteriole vessel that branches from an interlobular artery and supplies the glomerulus acinus cells arranged into a circular secretory unit (i.e. pancreatic acinus and mucous acinus) afferent lymphatic vessel a vessel involved in bringing lymph to the lymph node • Photomicrograph of afferent lymph vessel acrosome dense structure of the anterior portion of a sperm cell; contains enzymes that allow it to penetrate the egg during fertilization alpha-actinin protein that anchors actin to the Z-disk actin thin filament protein which allows contractility and confers support in cells alveolar duct long airway lined only with alveolar cells and some smooth muscle adenocarcinoma malignant cancer with cells arranged in a gland-like pattern; i.e. prostate and breast adenocarcinoma alveolar macrophage macrophage located in the alveolar space 3 and its surrounding connective tissue; serves to remove inhaled particles; also referred to as "dust cell" anterior chamber of eye space between the cornea and the iris; filled with aqueous humor alveolar sac alveoli cluster surrounding an air space; found at the end of alveolar ducts anterior lobe see adenohypophysis anthracoid pigment black debris found in the alveolar macrophages of those individuals chronically exposed to smoke • Photomicrograph of anthracoid in dust cell alveolar wall the site where alveoli exchange gas with the blood; composed of: • alveolar epithelium • alveolar basal lamina • endothelial basal lamina • endothelium antigen-presenting cell a cell that processes and presents antigens to lymphocytes; this category includes: • macrophages • Kupffer cells • reticular cells • Langerhans cell alveolus 1) the basic unit of gas exchange; small air-filled chamber lined by squamous cells 2) mammary gland secretory structure; lined by cuboidal cells and myoepithelial cells • Photomicrograph of alveolus antrum cavity inside the secondary and Graafian follicles amnion innermost membrane surrounding the embryo • Photomicrograph of amnion apical surface that side of the cell facing the lumen; typically the site of secretion and reception of substances (i.e. hormones, antibodies, and nutrients) ampulla of uterine tube see oviduct anal apocrine gland gland of the anus associated with hair follicles apocrine sweat gland large sweat gland associated with hair follicles in the eyelid, axilla, areola, anal region, and genitalia anal gland branched, straight tubular mucus gland extending into the submucosa apoptosis controlled cellular death in which the organelles are packaged in membranes for eventual phagocytosis; apparent as a shrinkage in cell size and a pyknotic nucleus anal transitional zone (ATZ) area where the simple columnar epithelium of the rectal mucosa meets an area of stratified squamous epithelium appositional growth bone growth due to addition of new matrix by osteoblasts in bone or chondroblasts in cartilage anchoring villi see basal plate 4 atrophy a wasting away of muscle due to denervation or disuse APUD cell endocrine cell of the digestive tract; activated by nervous stimulation • Photomicrograph of APUD cell Auerbach's plexus ganglion cell group between the two muscle layers of the muscularis externa in the digestive tract; controls motility of the digestive tract aqueous humor watery fluid of the anterior chamber and posterior chamber of eye arcuate artery branch of the interlobar artery; traces a course along the base of the renal pyramid axon extension of neurons which transmits signals to other neurons or effector cells • Photomicrograph of axon arcuate vein vessel carrying blood away from the kidney medulla; traces a course along the pyramid base axon hillock the point from which the axon emerges from the neuron body arrector pili muscle small muscle attached to the base of a hair follicle azurophilic granule the lysosome of leukocytes arteriole vessel with 1-2 layers of smooth muscle; leads to a capillary • Photomicrograph of arteriole B artery vessel which takes oxygen-rich blood from the heart to tissues ascites fluid found in the peritoneal cavity; consists of mesothelial cells, red blood cells, leukocytes and may contain cancer cells • Photomicrograph of ascitic fluid BALT Bronchus Associated Lymphatic Tissue; lymphatic aggregations of the respiratory system atherosclerotic plaque necrotic mass of lipid and cells (macrophages, smooth muscle cells, and fibroblasts) resulting from endothelial damage band cell (neutrophilic) precursor to the neutrophil with an "S" shaped nucleus • Photomicrograph of neutrophilic band cell atretic follicle disintegrating follicle within the ovary; has not undergone ovulation band form juvenile/immature forms of granulocytes with "U" or "S" shaped nuclei; immediate precursors to the mature forms 5 • Photomicrograph of neutrophilic band cell sesses vasoactive and immunoreactive substances similar to those of mast cells which are released after IgE binding; nucleus often obscured by coarse cytoplasmic blue (H&E) granules in cytoplasm. • Photomicrograph of basophil 2) cell of the adenohypophysis which stains blue-purple; includes: adrenocorticolipotropes, gonadotropes, and thyrotropes • Photomicrograph of pituitary basophil basal body structure derived from the centriole which organizes the microtubules of cilia • Photomicrograph of basal body basal cell a cell type that comprises the bottom layer of epithelia; serves as precursor/replacement for the cells above it • Photomicrograph of basal cell basophilic erythroblast erythrocyte precursor slightly smaller than the proerythroblast; has deeply basophilic cytoplasm; EM reveals considerable numbers of polyribosomes present (beginning of hemoglobin synthesis at this stage); division of basophilic erythroblast gives rise to polychromatophilic erythroblast • Photomicrograph of basophilic erythroblast basal lamina noncellular, protein-polysaccharide layer which anchors an epithelium to the connective tissue beneath; also known as 'lamina densa' known in light microscopy as basement membrane basal plate maternal side of the placenta; many blood vessels traverse here to supply the intervillous space; contains numerous anchoring villi which attach it to the chorionic plate • Photomicrograph of basal plate bile product of the liver stored in the gallbladder and released into the duodenum; allows for solubilization and uptake of lipids basal surface that side of the cell that is anchored to the basal lamina or to other cells; faces away from the lumen bile canaliculus "canal" between two adjacent hepatocytes; site of bile release from the hepatocyte • Photomicrograph of bile canliculus basement membrane Light microscopic term for basal lamina bile duct ducts which carry bile from the liver parenchyma; bile ducts fuse to form the hepatic duct • Photomicrograph of bile duct • Photomicrograph of bile duct basilar membrane membrane within the cochlea; its vibrations allow for frequency determination, with high frequency sounds discriminated at the base, and low frequency sounds at the apex • Photomicrograph of basilar membrane blast cell the earlier precursor of blood cells blood vessel structure that carries blood and bloodborne substances; lined by smooth muscle; basophil 1) least in number of all leukocytes; pos6 types include: • artery • arteriole • venule • vein • capillary site of plasma filtration; a double-layered cup-shaped structure that surrounds the glomerulus Bowman's gland "olfactory gland"; the secretion of this serous glands traps and dissolves odorproducing particles in the nasal cavity to allow for new smells to be detected blood-testis barrier the junctional complex between adjacent Sertoli cells; keeps developing germ cells isolated from potentially harmful antibodies of the circulation Bowman's membrane basal lamina of the corneal epithelium • Photomicrograph of Bowman's membrane • Photomicrograph of corneal epithelium blood-thymus barrier a barrier between lymphocytes and the lumen of vessels in the thymus; consists of: • capillary endothelium • basal lamina • connective tissue containing macrophages • basal lamina of epithelioreticular cells • epithelioreticular cell layer bronchial artery branches of this vessel supply all lung tissue except for the alveoli • Photomicrograph of bronchial artery • Photomicrograph of bronchial artery B-lymphocyte see lymphocyte bronchial vein this vessel drains the connective tissue of the lung hilus bone specialized connective tissue with a mineralized (hydroxyapatite) matrix bronchiolar cell also known as "Clara cell"; nonciliated cell lining bronchioles that secretes a lipoprotein to prevent adhesion of the airway walls • Photomicrograph of Clara cell bone marrow blood-rich material in the center of bone; involved in hemopoiesis • Photomicrograph of bone marrow bronchiole structure extending from the bronchi to the alveoli • terminal bronchiole- lined with ciliated cuboidal cells and bronchiolar cells; scattered brush cells and a circumferential smooth muscle layer are also notable features • respiratory bronchiole- continues after the terminal bronchiole; bronchiolar cells are abundant; some gas exchange can occur here; alveoli extend from the ter- bone-lining cell flat cell that aligns bone surfaces; is an inactive osteoprogenitor cell • Photomicrograph of bone-lining cell bony callus stage in bone repair; replaces the fibrocartilaginous callus after mineralization Bowman's capsule 7 • minal ends of this structure • Photomicrograph of bronchiole Photomicrograph of canaliculus cancer cell cell that exhibits uncontrolled growth; may spread throughout the organism affected bronchus see trachea Brunner's gland submucosal mucous glands of the duodenum • Photomicrograph of duodenal gland capillary a small blood vessel which receives from arteries and delivers to veins; thin endothelium is ideal for exchange of substances • Photomicrograph of capillary brush border the appearance of the numerous microvilli of an absorptive epithelium • Photomicrograph of brush border capillary space the side opposite the urinary pole in the glomerulus; contains blood brush cell a columnar epithelial cell of the respiratory system with numerous microvilli; serves as a sensory receptor; basal surface is in contact with a nerve ending capsular matrix material of the capsule consisting of sulfated proteoglycans capsule 1)a covering layer of connective tissue of the lymph node, spleen, testis, prostate and other organs • Photomicrograph of lymph node capsule 2)secreted matrix surrounding the lacunae of chondrocytes • Photomicrograph of cartilage capsule C calcified cartilage a stage of endochondral bone formation in which cartilage previously laid down is mineralized carcinoma in situ (CIS) a condition in which cancer cells are limited (at least temporarily) by the basement membrane from spreading to other areas canal of Schlemm opening at the corneal-scleral junction which drains the aqueous humor • Photomicrograph of canal of Schlemm cardiac gland gland located within the stomach at its junction with the esophagus; similar in property to the esophageal cardiac gland canaliculus "tunnel" which allows osteocytes housed in separate lacunae to communicate via cytoplasmic processes cardiac muscle involuntary, striated muscle that makes up the mass of the heart and lines some large vessels (i.e. large branches of the pulmo8 central artery name for the splenic artery within the white pulp • Photomicrograph of central artery nary vein) • Photomicrograph of cardiac muscle cardiac myocyte the elongate cell whose contractile and electric communication properties allow the heart to beat • Photomicrograph of cardiac myocyte central vein large vessel which drains the hepatic sinusoids • Photomicrograph of central vein cartilage tissue consisting of chondrocytes and a surrounding matrix; types include: • elastic cartilage- cartilage with high content of elastic fibers; found in external ear, epiglottis, and larynx • Photomicrograph of elastic cartilage • fibrocartilage- cartilage with high content of dense regular connective tissue; found in intervertebral discs, menisci, and the articular discs • Photomicrograph of fibrocartilage • hyaline cartilage- cartilage with an amorphous matrix; found in articular joints, tracheal rings, and knee cartilage • Photomicrograph of hyaline cartilage centriole cellular stucture involved in organizing the microtubular apparatus and also the mitotic spindle which is needed for faithful division of genetic material in cellular division centroacinar cell a cell of the proximal intercalated duct within the pancreatic acinus • Photomicrograph of centroacinar cell cervical gland mucous gland of the cervical mucosa; secretes less viscous mucous during midmenstrual cycle cervical mucosa lining of the head of the uterus (cervix); contains large branched glands; does not undergo sloughing cartilage plate supporting structure found in good number in the bronchi; becomes smaller and less numerous in smaller bronchial branches cervical myometrium see myometrium cartilage ring C-shaped hyaline cartilage which maintains the tubular shape of the trachea and the main bronchi cervical stroma see stroma cell body the main mass of the cell, from which various processes may extend Chief cell basophilic cell of the stomach fundic gland that secretes pepsinogen and a weak lipase • Photomicrograph of Chief cell cell lineage the full developmental stages of a given cell chondroblast a cell that secretes cartilage matrix; referred to as chondrocyte when surrounded 9 by matrix • Photomicrograph of chondroblast cell of the adenohypophysis which does not stain • Photomicrograph of chromophobe chondrocyte see chondroblast • Photomicrograph of chondrocyte chromosome paired chromatids joined by a centromere; the chromatids consist of chromatin; humans possess 23 paired chromosomes chondrogenic layer a region of cartilage formation ciliary body tissue located between iris and choroid; produces the aqueous humor and houses muscles which control lens shape • Photomicrograph of ciliary body chorionic plate fetal part of the placenta from which chorionic villi project • Photomicrograph of chorionic plate • Photomicrograph of chorionic plate ciliary muscle smooth muscle of the ciliary body that controls the shape of the lens chorionic villus finger-like extension of the chorionic plate which allows for maternal-fetal blood exchange; lined on the outer surface by the syncytiotrophoblast and cytotrophoblast and contains a core of fetal blood vessels; the intervillous spaces contain maternal blood; this arrangment allows for maternal-fetal exchange • Photomicrograph of intervillous space • Photomicrograph of chorionic villus • Photomicrograph of chorionic villus ciliated columnar epithelium the typical epithelium of the respiratory system; the cilia serve to move mucus and inhaled particles • ciliated epithelium ciliated epithelial cell cell equipped with cilia; primarily in the respiratory system and the oviduct cilium projection of certain cells containing microtubules which allows for cellular movement or the propulsion of other particles (i.e. mucus, an oocyte, etc.) • Photomicrograph of cilium choroid vascular layer which provides nutrition to the retina • Photomicrograph of choroid circular fiber of ciliary muscle allows lens to become more spherical chromaffin cell cell of the adrenal medulla which secretes epinephrine and norepinephrine • Photomicrograph of chromaffin cell circumvallate papillae large, dome-shaped structures anterior to the sulcus terminalis of the tongue which contain taste buds chromatin a tightly packed complex of DNA and histones (proteins) located in the nucleus Clara cell see bronchiolar cell chromophobe classical lobule 10 • Type I: located in skin, bone, tendon, and ligaments; allow for resistance to force, tension, and stretch • Type II: found in hyaline and elastic cartilage; provide resistance to pressure • Type III: connective tissue of organs and blood vessels; provide structural support • Type IV: basal laminae of epithelia and endothelium • Type VII: present in anchoring fibrils that secure the basal lamina to connective tissue hexagonal model of liver organization with six portal triads surrounding a central vein cleft of Schmidt-Lantermann spaces within the myelin sheath containing Schwann cell cytoplasm closed circulation theory a model for splenic circulation in which blood empties from splenic arterioles into the sinuses of the red pulp cochlea the coiled structure located in the inner ear that houses the auditory apparatus • Photomicrograph of cochlea (spiral ganglion) collecting duct duct of the kidney cortex and medulla that drains the tubule network into the larger ducts of Bellini; lined by squamous cells, cuboidal cells, and columnar epithelial cells, in that order as the duct increases in size cochlear canal space divided into the scala vestibuli superiorly and scala tympani inferiorly and the scala media in the center collecting tubule tubule that emerges in the cortical labyrinth; a number of these merge to form a collecting duct within a medullary ray cochlear duct A triangular space bordered by the basilar membrane, Reissner's membrane, and the lateral cochlear wall collecting vein same as central vein cochlear nerve the auditory portion of the vestibulocochlear nerve (CN VIII) colloid gel-like material of the follicles; site of thyroglobulin storage collagen bundle a large grouping of collagen fibers columnar epithelial cell a cell which is taller than it is wide; lines large glands and ducts; ideal for absorptive epithelia collagen fiber see collagen collagen fibril the basic functional and structural unit of collagen fibers consisting of a repeating pattern of collagen molecules in a banded array common bile duct structure which drains the cystic and hepatic duct into the duodenum compact bone bone characterized by heavy matrix deposition; confers great tensile strength; also known as 'cortical' bone collagen a triple helix protein which allows for great tensile strength; types include: 11 conducting portion structures of the respiratory system which bring air to the sites of gas exchange; include: • nasal cavity • nasopharynx • larynx • trachea • main bronchi corpus cavernosum see erectile tissue corpus luteum after ovulation, the collapsed Graafian follicle gives rise to this endocrine structure; produces progesterone and estrogen • Photomicrograph of corpus luteum cone photoreceptor cell responsible for color vision corpus spongiosum see erectile tissue cortex 1) the outer layer of the lymph node and thymus; contains high concentration of lymphocytes • Photomicrograph of thymus cortex 2) the outer portion of a given organ • Photomicrograph of lymph node cortex 3) the outer portion of the adrenal gland; comprised of the (outer to inner): • zona fasiculata • zona glomerulosa • zona reticularis o Photomicrograph of adrenal cortex conjunctiva mucus membrane lining the space between inner eyelids and surface lateral to the cornea connective tissue supportive tissue; includes: • loose connective tissue and dense connective tissue • specialized connective tissue: blood, bone cartilage, lymphatic tissue • embryonic tissue: mesenchyme, mucous connective tissue continuous capillary capillaries with a continuous endothelium; present in muscle, lung, and the CNS cortical labyrinth the combination of the renal corpuscle, the proximal and distal tubules • Photomicrograph of cortical labyrinth cornea chief refractive element and anterior window of the eye cortical sinus also known as "subcapsular sinus"; area under the capsule where the afferent lymphatic vessels drain; lined by myoepithelial cells • Photomicrograph of cortical sinus • Photomicrograph of cortical sinus • Photomicrograph of cortical sinus coronary artery a vessel that brings blood to heart tissue coronary vein a vessel that takes deoxygenated blood away from heart tissue corpus albicans a degenerated corpus luteum; filled with lipid and hyaline • Photomicrograph of corpus albicans corticotrope cell of the pituitary which stimulates release of hormones by the adrenal cortex 12 crypt area of the tonsil that contains large amounts of lymphocytes dendrite the signal receiving appendage of neurons crypt of Lieberkuhn mucous gland of the intestinal mucosa • Photomicrograph of crypt of Lieberkuhn dense irregular connective tissue connective tissue with randomized arrangement of abundant collagen fibers and sparse cellular content (i.e. submucosa) • Photomicrograph of dense irregular connective tissue cuboidal cell a cell with even dimensions on all sides; serves for absorption, barrier, and especially duct-lining • Photomicrograph of cuboidal epithelial cell dense regular connective tissue connective tissue with ordered and densely packed fibers (i.e. collagen) and cells; provides significant strength; see also tendon cytotrophoblast derivative of the trophoblast (a segment of the blastocyst which gives rise to the supportive structures of the embryo) that is mitotically active and fuses with the syncytiotrophoblast • Photomicrograph of cytotrophoblast dermal papillae connective tissue evaginations from the dermis into the epidermis • Photomicrograph of dermal papillae dermis the inner layer of the skin; composed of dense irregular connective tissue Descemet's membrane basal lamina of the corneal endothelium • Photomicrograph of Descemet's membrane D desmosome a strong adhesion on the lateral surfaces of cells; the strength is imparted by intermediate filament; also known as 'macula adherens' decidual cell cells of the endometrial stroma which, under the influence of estrogen and progesterone, store large amounts of glycogen; this creates a favorable environment for implantation of the blastocyst; appears as large, pale cell • Photomicrograph of decidual cell diapedesis process of lymphocyte migration through the blood vessel lining diaphysis the shaft of a long bone deep cortex area of the lymph node cortex which is adjacent to the medulla; T-lymphocytes are abundant here dilator pupillae muscle increases the iris (pupil) opening 13 distal convoluted tubule a tortuous tubule of the cortex lined by cuboidal cells; exchanges sodium for potassium, reabsorbs bicarbonate, and converts ammonia to ammonium; houses the macula densa • Photomicrograph of DCT • Photomicrograph of DCT cells of this epithelium possess stereocilia which move maturing spermatozoa through the channel • Photomicrograph of epididymis duodenal gland see Brunner's gland duodenum the initial portion of the intestine; receives contents of the stomach • Photomicrograph of duodenum distal straight tubule tubule of the medullary ray lined by cuboidal cells • Photomicrograph of distal straight tubule dust cell see alveolar macrophage • Photomicrograph of dust cell dome-shaped cell cell of the bladder which changes shape according to the state of distension dorsal surface of the tongue the top surface of the tongue which is covered with papillae E duct conduit that delivers substances from site of production to target site; sweat ducts are typically simple cuboidal epithelium or stratified cuboidal epithelium • Photomicrograph of duct early spermatid one of the more mature spermatozoan precursors; it is a round cell that is attached to the apical membrane of a Sertoli cell • Photomicrograph of early spermatid ductuli efferentes structure that connects the rete testis to the ductus epididymis; lined by pseudostratified columnar epithelium • Photomicrograph of ductuli efferentes eccrine sweat gland sweat gland found all over the body except the lips and external genitalia • Photomicrograph of sweat gland ductus deferens same as vas deferens; leads from the ductus epididymis to the prostatic urethra; lined by pseudostratified columnar epithelium • Photomicrograph of ductus deferens efferent arteriole drainage vessel of the glomerulus efferent lymph vessel a vessel that takes lymph away from the lymph node ductus epididymis highly coiled tube lined with pseudostratified columnar epithelium; the principal ejaculatory duct 14 the ductus deferens and the duct of the seminal vesicle form this structure in the body of the prostate gland; empties into the urethra in all long bones endolymph fluid of the membranous labyrinth of the inner ear elastic artery vessel with dense concentration of elastic laminae in the tunica media; i.e. aorta endometrium lining of the uterus and cervix consisting of two layers: • stratum basale- retained during menstruation; serves as stem source for regeneration of the upper stratum functionale • stratum functionale- thick part of endometrium; lost upon menstruation the uterine lining undergoes changes during the menstrual cycle: 1. proliferative phase- estrogen regulated; thickening of uterine glands, proliferation of stroma, growth of spiral artery o Photomicrograph of proliferative phase 2. secretory phase- progesterone regulated; very thick endometrium; uterine glands and spiral arteries coil o Photomicrograph of secretory phase 3. menstrual phase- rupture of vessels; sloughing of the endometrium; overall loss in endometrial mass o Photomicrograph of menstrual phase elastic cartilage see cartilage elastic cartilage matrix consists primarily of elastic fibers elastic fiber connective tissue fiber that allows for flexibility; composed of the protein elastin • Photomicrograph of vestibular membrane elastic laminae elastic fibers arranged in concentric layers: • inner elastic lamina- located in tunica intima • external elastic lamina- located between tunica media and tunica adventitia elastin polypeptide component of elastic fibers endocardium the heart wall layer which contacts blood; consists of outer endothelial layer and inner subendothelial layer of connective tissue endomysium connective tissue layer of reticular fibers surrounding muscle fibers endoneurium connective tissue which surrounds individual nerve fibers endocervix the part of the cervix facing inward toward the uterus; see also squamocolumnar junction • Photomicrograph of cervix endosome membrane-enclosed compartment surrounding a particle/cell that was phagocytosed endochondral bone formation a process of bone formation involving a cartilaginous precursor which is later mineralized and replaced with bone; occurs endosteum lining of the bone surface facing the mar15 row and also of trabeculae; consists of osteoprogenitor cells that are referred to as "endosteal cells" • Photomicrograph of endosteum fied squamous epithelium that comprises the upper skin layer; extensive keratin deposition allows for effective barrier function; has five strata (from inner to outer): • basale- contains stem cells o Photomicrograph of stratum basale • spinosum- large cells with ovoid nuclei o Photomicrograph of stratum spinosum • granulosum- cells rich with keratohyalin o Photomicrograph of stratum granulosum • lucidum- found in thick skin only; keratinization is beginning in these cells o Photomicrograph of stratum lucidum • corneum- cells without nuclei and filled with keratin o Photomicrograph of stratum corneum endotendineum connective tissue which surrounds a fasicle (the subunit of a tendon); contains vessels and nerves endothelial cell squamous cell that lines blood and lymphatic vessels • Photomicrograph of endothelial cell • Photomicrograph of endothelial cell endothelium 1)layer of endothelial cells and their underlying basement membrane; lines all but the smallest vessels 2)the deepest layer of the cornea • Photomicrograph of corneal endothelium epimysium dense connective tissue that surrounds a group of muscle fiber fascicles (bundles) entero-endocrine cell see APUD cell epinephrine also known as "adrenaline"; hormone of the adrenal medulla; involved in the sympathetic response eosinophil leukocyte with bilobed nuclei; engages in phagocytosis of antigen-antibody complex; possesses histaminase and other enzymes which neutralize the substances released by mast cells and basophils to prevent hyperinflammation; bilobed nucleus (humans); rodent eosinophils have annular shaped nucleus and monkeys eosinophils contain multilobed nuclei; have red granules (H&E) in cytoplasm • Photomicrograph of eosinophil • Photomicrograph of eosinophil epineurium connective tissue that binds bundles of nerve fibers • Photomicrograph of epineurium epiphyseal plate cartilaginous layer at the epiphysis of long bones which is the site of longitudinal bone growth epicardium see pericardium epiphysis the ends of long bones epidermis outer layer of skin; the keratinized strati- epitendineum connective tissue layer that surrounds a 16 excretory duct see duct; in esophagus: lined by stratified squamous epithelium as it emerges from the esophageal gland tendon epithelioreticular cell stellate-shaped cell that serves a supportive role in the thymus • Photomicrograph of epithelioreticular cell exocervix the segment of the cervix facing the vaginal space; see also squamocolumnar junction erectile tissue the corpus cavernosum and the corpus spongiosum which when engorged with blood, allow for erection external anal sphincter muscle voluntary sphincter of the anus • Photomicrograph of external anal sphincter ergastoplasm another name for the rough endoplasmic reticulum external elastic lamina see elastic laminae erythrocyte see red blood cell external elastic membrane same as external elastic lamina erythropoiesis the process of red blood cell formation, occurs in the bone marrow external root sheath outer layer of the hair follicle; derived from a downgrowth of the epidermis erythropoietin a kidney protein which stimulates erythropoeisis in times of reduced tissue oxygen exudate debris material containing dead leukocytes and foreign cells found at sites of infection esophageal cardiac gland gland of the terminal esophagus; located in the lamina propria; secretes a neutral mucus to protect the esophagus from gastric regurgitation eyelash a hair of the eyelid eyelid protects the eye from foreign objects and desiccation esophageal gland occurs throughout the esophageal submucosa; secretes a slightly acid secretion which lubricates the esophageal lumen estrogen steroid hormone which maintains/develops female sex characteristics euchromatin light-staining matter of the nucleus; represents less condensed, more actively transcribed DNA regions F 17 fibromuscular stroma dense irregular connective tissue and smooth muscle of the prostate gland F-actin filamentous actin composed of two Gactin (globular actin) strands filiform papillae appendages on the dorsal surface of the tongue; covered with keratinized stratified squamous epithelium • Photomicrograph of filiform papillae fascia adherens plates on the transverse intercalated disc that allow muscle cells to anchor to each other; analogous to the zonula adherens of epithelial cells fimbriae finger-like extensions of the infundibulum which catch the oocyte after its departure from the ovary fenestrated capillary capillary with a discontinuous basal lamina as well as gaps (covered by diaphragms) between the endothelial cells fixed cell a cell that is a resident of connective tissue; i.e mast cell fenestrated cortical sinusoidal capillary see sinusoidal capillary foam cell a macrophage containing large lipid stores; located within an atherosclerotic plaque • Photomicrograph of foam cells fenestration membrane a discontinuous basal lamina of a fenestrated capillary covered by a diaphragm fibroblast Fusiform cell with cytoplasm that is usually indistinguishable from the surrounding matrix; tapering processes are present but are difficult to visualize in most sections; some very active cells have basophilic cytoplasm; has elliptical nucleus, sometimes slightly folded, with sparse chromatin that presents a "speckled" appearance (may be mistaken for plasma cell); has one to two nucleoli; makes fibers and ground substance • Photomicrograph of fibroblast foliate papillae appendages of the dorsolateral surface of the tongue; contain many taste bud • Photomicrograph of foliate pupillae follicle 1) the spherical structure responsible for hormone production in the thyroid gland • Photomicrograph of thyroid follicle 2) see hair follicle follicle stimulating hormone (FSH) pituitary hormone which stimulates the maturation of the ovarian follicle fibrocartilage see cartilage follicular cell the cuboidal cell of the thyroid follicle or the developing follicle • Photomicrograph of thyroid follicular cell • Photomicrograph of ovarian follicular cell fibrocartilaginous callus a stage of bone repair in which fibrocartilage is deposited to stabilize the ends of the fractured bones; later replaced by the bony callus 18 folliculogenesis the process of follicular development; includes several stages (in the following order): • primordial follicle- oocyte surrounded by flattened follicular cells o Photomicrograph of primordial follicle o Photomicrograph of primordial follicle • primary follicle- oocyte surrounded by cuboidal cells o Photomicrograph of primary follicle • secondary follicle- theca interna, theca externa, and antrum present o Photomicrograph of secondary follicle • Graafian follicle- mature follicle; all structures of secondary follicle plus a cumulus oophorus surrounding the oocyte o Photomicrograph of Graafian follicle G-actin "globular" actin, appears bead-like in structure GALT Gut Associated Lymphatic Tissue; lymphatic aggregates located throughout the digestive tract ganglion a group of neuronal cell bodies • Photomicrograph of sympathetic ganglion ganglion cell 1) a cell of a ganglion 2) postganlionic cell of the adrenal medulla; causes release of norepinephrine and epinephrine upon nervous stimulation • Photomicrograph of ganglion cell • Photomicrograph of ganglion cell fundic gland simple, branched tubular gland of the stomach fundus that produces the substances necessary for digestion; contains Chief cells, mucous neck cells, parietal cells, APUD cells, and stem cells ganglion cell layer layer of the neural retina which houses neurons involved in transmitting the signals of photoreception gap junction channel that allows electrical, electrolyte, and fluid communication between adjacent cells; also known as nexus fungiform papillae mushroom-shaped appendages of the dorsal tongue; contain numerous taste buds gastric gland another name for fundic glands gastric pit depression of the stomach lining that opens into the gastric gland germinal center area of lymphatic tissue containing rapidly developing/differentiating lymphocytes • Photomicrograph of germinal center G 19 germinal epithelium cuboidal cells that line the surface of the ovary; does NOT give rise to germ cells Graafian follicle see folliculogenesis granulocyte neutrophils, eosinophils, and basophils, all of which possess certain immunoreactive substances contained in granules gland structure involved in producing substances to be secreted; sweat glands tend to be lined by either stratified cuboidal epithelium or stratified columnar_epithelium granulopoiesis the developmental process of granulocytes glomerular basement membrane GBM; basal lamina between the podocytes and endothelium; allows selective permeability by size and charge (positive, small particles filter easier granulosa cell cell which comprises a layer which surrounds the antrum of the mature follicle; catalyzes the conversion of androgens to estrogen • Photomicrograph of granulosa cell glomerulus capillary meshwork of the kidney nephron granulosa lutein cell cell of the corpus luteum derived from the granulosa cell • Photomicrograph of granulosa lutein cell glucocorticoid see zona fasciculata glycogen primary energy storage form of animal cells; appear as empty vacuoles in LM ground substance viscous substance that occupies the space between fibroblasts and connective tissue goblet cell special mucus-secreting columnar epithelial cell located in the respiratory system and intestines; large vacuoles can be seen in light microscopy • Photomicrograph of goblet cell H Golgi complex cellular structure involved in modifying, packaging, sorting, and secreting proteins; has cis face for receiving and trans face for releasing products • Photomicrograph of Golgi complex H band a region of the sarcomere with only myosin filaments; shortens with contraction gonadocorticoid LH and FSH; released by the gonadotropes hair appendage of the skin composed of keratinized cells gonadotrope cell of the adenohypophysis which releases LH and FSH hair cell 20 the cell of audioreception protruding from the basilar membrane; registers vibration, which is then converted to electrical signals transmitted along the cochlear nerve hemopoiesis process of blood cell formation from a common stem cell; occurs in bone marrow in the adult hair follicle skin structure from which hairs arise hemosiderin debris found in heart failure cells • Photomicrograph of hemosiderin in a dust cell Hassall's corpuscle concentric arrangement of epithelioreticular cells; more prominent in adults • Photomicrograph of Hassal's corpuscle • Photomicrograph of Hassal's cprpuscle Haversian canal see Haversian system • Photomicrograph canal of hepatic acinus see liver acinus hepatic artery vessel carrying oxygen rich blood to the liver • Photomicrograph of hepatic artery • Photomicrograph of hepatic artery Haversian hepatic duct duct which delivers bile from the liver to the cystic and common bile ducts Haversian system concentric lamellae arranged around a central (Haversian) canal which conatins blood vessels and nerve supply hepatic sinusoid sinusoids of the liver • Photomicrograph of hepatic sinusoid • Photomicrograph of hepatic sinusoid heart failure cell alveolar macrophage filled with hemosiderin; indicative of congestive heart failure helper T-lymphocyte a cell that stimulates B-lymphocytes and T-lymphocytes to carry out their respective functions hepatic vein drains deoxygenated blood from the liver to the inferior vena cava hematopoiesis same as hemopoiesis hepatocyte the basic functional cell of the liver • Photomicrograph of hepatocyte hemidesmosome structure on the basal surface of an epithelial cell that anchors it to connective tissue elements Herring body axonal dilation within the neurons of the pars nervosa; contains either oxytocin or vasopressin • Photomicrograph of Herring body hemocytoblast large cell with basophilic cytoplasm and large nucleus which was at one time considered to be the precursor to all blood cell types heterochromatin dark staining regions of chromatin in the nucleus; signifies DNA regions of little 21 I transcripitional activity hilus the area of a lymph node where vessels enter and exit Hofbauer cell macrophage-like cell of the chorionic villus; unknown function; contains stores of lipids and glycoproteins • Photomicrograph of Hofbauer cell I band a region of the sarcomere whose span includes only actin filaments • Photomicrograph of I band holocrine mode of secretion in which part of the secretory cell is exuded in the product; i.e. sebaceous gland ileum terminal portion of small intestine; opens into cecum of the large intestine immunoglobulin antibody secreted by the plasma cells; types include: • IgA- present in body secretions • IgD- on the surface of lymphocytes and is involved in their differentiation • IgE- stimulates mast cells to release immunoreactive substances • IgG- activates complements, which lyse bacteria; elemental in secondary response and passive immunity • IgM- activates macrophages; activates complements; primary Ig of primary response Howship's lacuna the space underneath an osteoclast where bone matrix is being resorped hyaline cartilage see cartilage hypertrophy overgrowth of cells due to: overstimulation of the tissue/organ which they comprise, a cancer, or a benign condition such as BPH (benign prostratic hypertrophy) hypodermis a layer of connective tissue beneath the dermis; contains ample adipose inactive mammary gland mammary gland with much dense irregular connective tissue and no secretory activity • Photomicrograph of inactive mammary gland hypophyseal portal system capillary network carrying neuroendocrine secretions from the median eminence and infundibular stem to the pars anterior inflammation bodily response to injury characterized by pain, swelling, redness, and loss of function; triggered by heavy infiltration of leukocytes, particularly neutrophils hypothalamohypophyseal tract nerve tract leading from the hypothalamus to the pituitary infundibulum 1)attachment between the hypothalamus and pituitary 2)see oviduct 22 tery and descends into a kidney lobule; a lobule is a segment of a lobe, which in turn consists of a pyramid and surrounding tissue on its base and sides • Photomicrograph of interlobular artery inner circumferential lamellae concentric rings of bone matrix closer to the bone center inner elastic membrane same as internal elastic lamina interlobular duct duct of the mammary gland; located at a distance from lobules inner limiting membrane layer of the neural retina composed of the basal lamina of Muller cells interlobular vein vessel that carries deoxygenated blood in the same region as the interlobular artery, but in reverse course • Photomicrograph of interlobular vein inner nuclear layer layer of neural retina housing horizontal, amacrine, bipolar and Muller cells inner plexiform layer contains processes of the cells of the inner nuclear layer intermediate filament cytoskeletal element which serves a general supportive and structural function intercalated disc structure which connects adjacent muscle fibers at their ends; also allows for communication via gap junctions which span it • Photomicrograph of intercalated disc intermediate lobe see pars intermedia internal anal sphincter muscle the involuntary, inner anal sphincter; composed of smooth muscle • Photomicrograph of internal anal sphincter intercalated duct located between an acinus and larger ducts in salivary glands; secrete bicarbonate and absorb chloride; most prominent in salivary glands that produce watery secretions • Photomicrograph of intercalated duct internal elastic lamina see elastic laminae internal elastic membrane same as internal elastic lamina intercellular bridge the actin filament bundles interposed between adjacent Sertoli cells interstitial growth process of bone/cartilage growth due to cell division rather than matrix deposition intercellular space a space between adjacent cells interstitial lamellae rows of bony matrix in the area between Haversian systems • Photomicrograph of interstitial lamellae interlobar artery branch of the renal artery; travels between adjacent renal pyramids interlobular artery vessel that branches from an interlobar ar- interterritorial matrix 23 in cartilage, material at a distance from cells; proteoglycans are in sparse concentration here; see also territorial matrix islet of Langerhans functional unit of the endocrine pancreas; composed of three cell types: • A cells- secrete glucagon • B cells- secrete insulin • D cells- secrete somatostatin • Photomicrograph of islet intervillous space see chorionic villus intestinal gland same as crypt of Lieberkuhn isogenous group group of contiguous chondrocytes that results from the division of a single precursor intracellular canaliculus invagination of the parietal cell membrane with numerous microvilli; this system enhances the surface area available for HCL release isthmus see oviduct intralobular duct 1) the equivalent of the striated duct; lined by cuboidal cells; functions in reabsorption of sodium and secretion of potassium; found in salivary glands and the pancreas • Photomicrograph of intralobular duct 2) duct leading from the mammary lobules to the interlobular duct Ito cell see lipocyte J intramembranous bone formation process in which bone is laid down by osteoblasts without a prior cartilaginous precursor; primary mode of flat bone formation • Photomicrograph of intramembranous bone formation jejunum middle portion of the small intestine junctional complex the combination of desmosomes, zonula adherens, and zonula occludens intrinsic striated muscles of tongue visceral striated muscle; allow for voluntary tongue movement juxtaglomerular apparatus structure adjacent to the afferent and efferent arterioles; it is involved in the release of renin, and hence the control of blood pressure; consists of: • juxtaglomerular cells (modified smooth muscle cells containing renin granules) • the macula densa • extraglomerular mesangial cells iridocorneal angle the space between where the iris and cornea are anchored iris diaphragm extending over the lens surface; controls pupil diameter islet cell see islet of Langerhans 24 juxtaglomerular cell see juxtaglomerular apparatus labial mucosa lining of the oral surface of the lip; consists of stratified squamous nonkeratinized epithelium lacteal a small lymphatic vessel located at the intestinal villus tip K lacuna the housing compartment of chondrocytes and osteocytes within their respective matrices • Photomicrograph of lacuna keratinized stratified squamous epithelium see epidermis lamina propria the loose connective tissue of mucous membranes keratinocyte cell of the epidermis which produces keratin Langerhans cell antigen-presenting cell of the stratum spinosum; has clear cytoplasm and darkstaining nucleus keratohyalin protein produced by the keratinocyte which becomes keratin when combined with tonofilaments (intermediate filaments) larynx air passage between the oropharynx and the trachea killer T-lymphocyte a cell of the immune system that directly attacks foreign cells, causing lysis late spermatid elongate spermatozoan precursor bordering the seminiferous tubule lumen, yet still attached to a Sertoli cell • Photomicrograph of late spermatid Kupffer cell cell of the mononuclear phagocytic system which resides in the space of Disse; degrades damaged erythrocytes • Photomicrograph of Kupffer cell lateral surface of epithelial cell that side of the cell in contact with other cells; usually anchored by various filament complexes layer of rods and cones layer of neural retina housing the photoreceptors L lens transparent, elliptical structure which along with the cornea, is a refractive element of the eye • Photomicrograph of lens epithe25 lipofuscin vacuole containing debris; the older a cell, the more lipofuscin it will contain; also known as tertiary lysosome and residual body lium lens capsule thick basal lamina covering the lens leukemia a cancer in which the numbers of leukocytes in the blood increase dramatically; immature blood cells are also found in circulation in this condition liver acinus elliptical model of liver organization with central veins on the ends of the long axis, and portal triads on the ends of the short longitudinal axis leukocyte a cell of the immune system; also known as a white blood cell lobe subdivision of the lung; the left lung is divided into an upper and lower lobe, the right lung is divided into an upper, middle, and lower lobe leutinizing hormone pituitary hormone which stimulates theca interna cells to secrete androgens lobule 1)a group of ducts and surrounding connective tissue within the mammary gland 2)the functional unit of liver organization; defined variously as: the classical lobule, the liver acinus, and the portal lobule 3)an area of the lung supplied by a bronchiole Leydig cell cell of the stroma surrounding the seminiferous tubule which produces testosterone; this hormone is important in the male for: • differentiation of CNS and genitalia • development of secondary sex characteristics • libido development • anabolic processes o Photomicrograph of Leydig cell longitudinal (meridional) fiber part of the ciliary muscle; causes tension of the lens limbus a transitional area between cornea and sclera loop of Henle a U-shaped structure of the nephron consisting of the descending proximal straight tubule, the thin segment, and the ascending distal straight tubule lipid fatty acids, cholesterol, etc. housed in cells as vacuoles loose connective tissue connective tissue with an abundance of cells and sparse fibers • Photomicrograph of loose connective tissue lipid droplet lipid vacuoles inside cells; usually lost in preparation for microscopy lipocyte also known as "Ito cell"; cell of the liver which stores large amounts of lipid as well as vitamin A lymph nodule aggregates of lymphocytes in the cortex of the lymph node lymphatic channel 26 same as lymphatic vessel each other lymphatic vessel a vessel that carries lymph, which consists of interstitial fluid, cells of the immune system, foreign cells, and other substances • Photomicrograph of lymphatic vessel macrophage massive cell involved in phagocytosis of foreign material or defective host cells, and in antigen presentation; usually irregular in shape with vacuolated cytoplasm; the macrophage is difficult to distinguish from a fibroblast without the presence of phagocytosed material • Photomicrograph of macrophage • Photomicrograph of macrophage • Photomicrograph of macrophage lymphocyte Small round cell with dark nucleus and only a thin rim of cytoplasm: • B-lymphocytes- involved in humoral response • T-lymphocytes- involved in cellmediated response o Photomicrograph of lymphocyte o Photomicrograph of lymphocyte macula adherens see desmosome macula densa specialized cell group of the distal convoluted tubule that is part of the juxtaglomerular apparatus • Photomicrograph of macula densa lymphopoiesis the process of development of lymphocytes in lymph nodes malignant acinus in prostate cancer, the presence of glandular hypertrophy • Photomicrograph of prostate cancer lysosome digestive organelles containing various hydrolytic enzymes; • Primary- newly formed as a bud from the Golgi • Secondary- primary lysosome fused to target material • Tertiary- vacuole containing remnants of the digestive process; also called "residual body" Mallory body eosinophilic inclusion found in the hepatocyte of alcoholics • Photomicrograph of Mallory body MALT mucosa associated lymphatic tissue; lymphatic aggregates of the cervical mucosa mammatrope acidophilic cell of the adenohypophysis which releases luteotropic hormone (LTH) M marginal zone area between the red pulp and white pulp of the spleen M band located in the sarcomere, a region at the center of the H band which signifies the attachment sites of myosin filaments to marrow see bone marrow 27 mast cell large fixed cell that has large granules containing immunoreactive and vasoactive substances: histamine, slow-reacting substance of anaphylaxis, eosinophilic chemotactic factor of anaphylaxis, and heparin; found near blood vessels; round small nucleus (as compared to cell size); numerous granules show metachromasia with some stains • Photomicrograph of mast cell medullary ray aggregate of the proximal, distal straight and collecting tubules • Photomicrograph of medullary ray medullary sinus space between adjacent medullary cord; drains lymph into the efferent lymph vessel • Photomicrograph of medullary sinus mature cell a cell after it has fully developed from its precursors; if applied to granulocytes, refers to the cell form of the circulation, which usually contains a multilobed segmented nucleus medullary vein also known as "central vein"; large, muscular vein of the adrenal medulla; its strong contractility facilitates quick release of the medullary hormones megakaryocyte a massive precursor of platelets within the bone marrow; possesses a multilobed nucleus • Photomicrograph of megakaryocyte median eminence continuous with the infundibulum; carries neurosecretory nerves mediastinum testis connective tissue that projects into the parenchyma of the testis, carrying with it blood and lymph vessels meiosis a process which produces daughter cells with half the DNA content of the parent; results in germ cell production medulla the inner portion of an organ; in the thymus and lymph node, area of relatively sparse lymphocyte concentration • Photomicrograph of thymus medulla Meissner's corpuscle receptors of low frequency tactile stimuli; located on hairless skin • Photomicrograph of Meissner's corpuscle medulla of lymph node inner portion which contains a lesser concentration of lymphocytes • Photomicrograph of medulla • Photomicrograph of medulla Meissner's plexus a ganglion of the submucosa which controls secretion in the digestive tract melanocyte a cell of the epidermis which produces melanin, the substance responsible for pigmentation • Photomicrograph of melanocyte medullary cord tissue of the medulla in lymph organs containing reticular cells, lymphocytes, macrophages, and plasma cells • Photomicrograph of lymph node medullary cord melanotrope cell of the pars intermedia which stimulates melanin production; found in some 28 non-human species metaphysis the curve between the ends of the bone (epiphysis) and the shaft of the bone (diaphysis) membrane coating granule found within the keratinocytes of the stratum spinosum; contains a glycolipid that forms a water barrier on the skin surface metastasis the spread of a cancer to areas away from where it originated menstrual phase of the endometrium see endometrium Merkel cell cell of stratum basale which functions in cutaneous sensation metastatic cancer cell cell involved in metastasis microbiological flora bacteria; found in certain body cavities; see Pap smear mesangial cell cell of the juxtaglomerular apparatus and renal corpuscle; involved in phagocytosis of debris • Photomicrograph of mesangial cell mesaxon slit left exposed on outer myelin sheath after myelin wrapping is complete microfilament cytoskeletal element involved in cell anchorage, contraction, exocytosis/endocytosis, structure of microvilli, and locomotion; actin and myosin are examples mesothelial cell squamous cell comprising the cellular part of the mesothelium • Photomicrograph of mesothelial cell microtubule cytoskeletal element found in cilia, flagella, basal bodies, the mitotic spindle, centrioles, cytoplasm, and elongating cell processes (i.e. axon) mesothelium epithelial lining of the body cavities (i.e. thoracic, pericardial, abdominal) microvilli processes of the apical plasma membrane of absorptive cells; increase surface area for absorption metachromasia phenomenon in which a basic dye changes color from blue to red/purple due to the dense presence of polyanionic groups (i.e. phosphates, sulfates) mineralocorticoids see zona glomerulosa minor calyx the point where the collecting ducts of a pyramid drain; several of these structures drain into a major calyx metamyelocyte precursor of granulocytes which shows varying degrees of indentation, and elongation of the nucleus indicative of differentiation into the more mature juvenile or band forms. • Photomicrograph of metamyelocyte (neutrophilic) mitochondria oxidative organelle of the cell; believed to be derived from a prokaryotic symbiote mitochondrial cristae 29 involutions of the inner mitochondrial membrane protruding into the matrix; contain enzymes of oxidative phosphorylation mucous acinus a mucous secretory unit with a circular arrangement of mucous cells • Photomicrograph of mucous acinus mitosis process which produces two daughter cells, each with genetic material equal in amount to the parent mucous cell a cell that produces and releases mucous; vacuoles are usually visible within the eosiniphilic cytoplasm mitotic cell cell in the process of dividing into two daughter cells which will contain the same amount of genetic material as the parent mucous gland cell a cell of a mucous gland located in the digestive tract, respiratory system, etc mixed spicule newly forming bone atop calcified cartilage; seen in endochondral bone formation mucous gland a gland that release mucous, a glycoprotein modiolus bony core around which the cochlea turns 2 and 3/4 times mucous neck cell located at the neck of the fundic gland; secretes a soluble mucous monoblast precursor of the promonocyte mucous-secreting cell see mucous cell monocyte the large blood-borne precursor of mononuclear phagocytic system cells; has some vacuoles and indented nucleus frequently lacking nucleoli • Photomicrograph of monocyte mucous surface cell cell lining the gastric pit; secretes an insoluble mucous muscle fiber see myofiber mononuclear phagocytic system cells capable of vigorous phagocytosis; arise from monocytes; this system includes: • macrophages • Kupffer cells • osteoclasts • Langerhans cell muscular artery most numerous of artery types; notable for thick, muscular tunica media; example is brachial artery • Photomicrograph of muscular artery muscularis see muscularis externa mucocutaneous junction the border between the epidermis of the outer lip and the labial mucosa muscularis externa located beneath the submucosa of the esophagus; consists of an inner circular and outer longitudinal layer mucosa the combination of an epithelial lining, the lamina propria, and muscularis muscosae 30 muscularis mucosa deepest layer of the mucosa; consists of an inner circular and outer longitudinal layer • Photomicrograph of muscularis mucosa contractile cell that lines glands; it contracts to cause secretion; i.e. the alveoli of the mammary gland are lined by these cells • Photomicrograph of myoepithelial cell myelin lipid-rich substance that is formed as a sheath by Schwann cells onto certain types of nerves; allows for rapid conduction • Photomicrograph of myelinated nerve • Photomicrograph of unmyelinated nerve myofiber also known as "myotube"; the muscle cell • Photomicrograph of vestibular membrane myofibril a unit of repeating sarcomeres; subunit of the myofiber myelin sheath see myelin • Photomicrograph of myelin sheath myofibroblast spindle-shaped cell that displays cytological characteristics of both fibroblasts and smooth muscle cells; elongated nucleus often exhibits an wavily profile; cytoplasm can be distinguished from the surrounding matrix due to the presents of actin filaments (and dense bodies at EMlevel); does not have basal (external) lamina; is seen usually as an isolated cell, although its processes may contact the processes of other myofibroblast (gap junctions at EM-level); contractile cell of connective tissue; major role in wound contraction myelinated axon see myelin myelinated nerve see myelin myeloblast precursor of the promyelocyte; have large nuclei myelocyte precursor in the granulocyte cell line; first one to contain specific granules; has slightly indented nucleus; also a reduction in the number of the azurophilic granules; cells are further distinguished according to the type ofgranules that develop, i.e., neutrophilic myelocyte (60%), eosinophilic myelocyte, basophilic myelocyte (3%); the nucleus of these cells is slightly indented; cells in this series divide and give rise to metamyelocytes • Photomicrograph of myelocyte myofilament functional and structural protein of muscle cells; see actin and myosin myoid cell a cell of the stroma surrounding the seminiferous tubule; has contractile properties and also secretes the stroma matter • Photomicrograph of myoid cell • Photomicrograph of myoid cell myocardium intermediate, bulky layer of the heart wall; comprised of numerous cardiac myocytes myometrium smooth muscle layer of the uterus myosin thick filament constituent protein which myoepithelial cell 31 together with actin allows for muscle contraction neurofilament intermediate filament located in axons function in axonal transport myotube see myofiber neurohypophysis posterior pituitary; contains neurosecretory tissue myotube nucleus nucleus of a myofiber neuron the nerve cell; allows for conduction and reception via specialized processes (axons and dendrites) N neutrophil also known as "polymorphonuclear leukocyte"; a leukocyte which engages actively in phagocytosis and is the main trigger for the inflammation response; multilobed nucleus with heterochromatin and no visible nucleolus; some granules in cytoplasm may stain light blue to pink depending on conditions • Photomicrograph of neutrophil • Photomicrograph of neutrophil neck of gastric gland see mucous neck cell nephron functional unit of the kidney; consists of a glomerulus and its tubular network • cortical nephron- has renal corpuscles in the outer cortex; has short loops of Henle • juxtamedullary nephron- has renal corpuscle near the base of a pyramid; has long loops of Henle Nissl body rough endoplasmic reticulum (rER) of the nerve cell node of Ranvier space between two adjacent Schwann cells which is a gap in the myelin sheath; allows for a jumping signal known as "saltatory conduction" • Photomicrograph of node of Ranvier • Photomicrograph of node of Ranvier nerve see nerve fiber nerve fiber structure comprised of the axon and its myelin sheath; a bundle of nerve fibers forms a nerve, which serves as a "cable" to communicate electrical signals throughout the body • Photomicrograph of vestibular membrane nonciliated cell those cells lacking cilia; see also oviduct non-keratinized stratified squamous epithelium see stratified squamous non-keratinized epithelium nervi vasorum nerve supply to vessels; located in the tunica adventitia 32 non-myelinated axon see myelin smell in the nasal cavity olfactory epithelium epithelium responsible for the sense of smell; consists of: • olfactory cells • sustentacular cells • basal cells • brush cells norepinephrine also referred to as "noradrenaline"; hormone of the adrenal medulla involved in the sympathetic response normoblast also known as "orthochromatophilic erythroblast"; erythrocyte precursor with heavy eosinophilic stain due to dense hemoglobin production • Photomicrograph of normoblast oocyte the developing female gamete oogenesis production of oocytes nuclear envelope the membrane surrounding the nucleus; continuous with the rough endoplasmic reticulum oogonia cells which give rise to primordial follicles open circulation theory model in which blood empties from splenic arterioles into the splenic cords and from there into the splenic sinuses nuclear pore opening in nuclear envelope which allows for transit of ribosomal subunits, mRNA, etc. optic nerve fiber layer layer of the neural retina containing the axons of the ganglion cells • Photomicrograph of optic nerve nucleolus site of ribosomal RNA synthesis; appears as dense structure within the nucleus • Photomicrograph of nucleolus oral mucosa see labial mucosa nucleus enveloped compartment containing the genetic material of the cell • Photomicrograph of nucleus orbicularis oculi muscle voluntary muscle which allows for eyelid closure nucleus of ganglion cell see nucleus orbicularis oris muscle striated, voluntary muscle of the lip organ a structure that performs a specific function (i.e. digestive action of stomach) O organ of Corti consists of hair cells and supporting cells atop the basilar membrane; it is the site of aufioreception when hair cells are stimulated by vibrations olfactory cell bipolar neurons that are the receptorsof 33 • Photomicrograph of organ of Corti layer of the neural retina housing the cell bodies of rods and cones osteoblast a flat, eosinophilic cell which secretes bone matrix • Photomicrograph of osteoblast outer plexiform layer layer of the neural retina containing the processes of rods, cones, bipolar, horizontal, and amacrine cells osteoclast a phagocytic cell involved in the resorption of bone matrix • Photomicrograph of osteoclast ovarian cyst structure seen in polycystic ovarian disease (PCOD); lined by granulosa cells and surrounded by hypertrophic theca interna cells • Photomicrograph of ovarian cyst osteocyte a mature osteoblast; has an ovoid shape • Photomicrograph of osteocyte ovarian stroma the supporting tissue of the ovary; contains much loose connective tissue, blood vessels, lymphatic vessels, and nerves osteoid unmineralized bone matrix secreted by osteoblasts • Photomicrograph of osteoid oviduct lined by ciliated cells and nonciliated ("peg") cells; tube leading from the ovary to the uterus; has four parts: • infundibulum- segment closest to ovary; its fimbriae catch the oocyte • ampulla- longest segment; site of fertilization • isthmus- narrow segment next to the uterus • intramural part- opens into the uterine cavity o Photomicrograph of oviduct o Photomicrograph of "peg cell" osteon see Haversian system osteoprogenitor cell cell contained in the periosteum, the fibrous layer which covers bone; gives rise to osteoblasts • Photomicrograph of osteoprogenitor cell outer circumferential lamellae concentric rings of bony matrix closer to the bone periphery than the center outer cortex the outer portion of the lymph node cortex containing nodules, which in turn house germinal centers ovulation the process of oocyte release from the Graafian follicle; occurs due to a sharp rise in leutinizing hormone (LH) outer elastic membrane see elastic laminae oxyphil round, acidophilic cell of the parathyroid with no known function • Photomicrograph of oxyphil outer limiting membrane layer between the layer of rods and cones and the outer nuclear layer outer nuclear layer 34 cell P parakeratinized epithelium epithelium of the mucocutaneous junction; analogous to the epidermis but with a top layer of cells that retain their nuclei • Photomicrograph of parakeratinized epithelium (lip) Pacinian corpuscle pressure receptor of the skin located in the dermis and hypodermis • Photomicrograph of Pacinian corpuscle parakeratosis disease state signified by retention of nuclei in the cells of the stratum corneum parathyroid gland ovoid gland associated with the thyroid gland; produces parathyroid hormone necessary for phosphate and calcium regulation • Photomicrograph of parathyroid gland pampiniform plexus unusually thick veins of the spermatic cord; have at least two smooth muscle layers • Photomicrograph of vein of pampiniform parenchyma the functional tissue of an organ; as opposed to its supportive elements (i.e. the stroma pancreatic acinar cell secretory cell of the pancreas; contain granules visible under LM pancreatic acinus circular secretory unit of the exocrine pancreas parenchymal cell any cell involved in the basic function(s) of a given tissue, i.e. hepatocyte of the liver Paneth cell specialized cell of the the small intestine that releases antibacterial substances and engages in phagocytosis; regulates the small intestinal flora population • Photomicrograph of Paneth cell parietal cell cell of the fundic gland that releases HCL and intrinsic factor • Photomicrograph of parietal cell parietal layer of Bowman's capsule outer layer of the capsule; consists of squamous cells Pap smear cytological exam conducted by scraping the vaginal and cervical lining; contains epithelial cells, granulocytes, microbiological flora, erythrocytes, and lymphocytes; may on occasion contain cancer cells parotid gland a serous gland of the oral cavity • Photomicrograph of parotid gland pars anterior also known as "pars distalis"; the main secretory portion of the adenohypophysis; three cell types within it are parafollicular cell cell located between thyroid follicles; secretes calcitonin • Photomicrograph of parafollicular 35 • • • acidophils basophils chromophobes serosa of the uterus perimysium connective tissue that surrounds a group of muscle fibers to form a fasicle pars intermedia part of the adenohypophysis with unknown function; secretes MSH in certain species perineurial cell a cell of the perineurium; has contractile property pars nervosa part of the neurohypophysis which has neurosecretory nerve endings perineurium connective tissue which surrounds a nerve fiber bundle pars tuberalis part of the adenohypophysis which encircles the pars intermedia periosteum dense connective tissue layer that surrounds bone; contains osteoprogenitor cells • Photomicrograph of periosteum penicillar artery branch of the central artery of the spleen as it enters the red pulp peritubular capillary branch of the efferent arteriole which supplies and exchanges substances with the tubular network of the nephron periarterial lymphoid sheath "PALS"; layer of lymphocytes aggregated around the central artery of the spleen pericardium mesothelial layer surrounding the outer heart surface; contains vessels and nerves supplying the heart peroxisome oxidative organelle; also known as 'microbody'; contains catalase and other peroxidases to break down hydrogen peroxidase produced from oxidative processes perichondrium dense irregular connective tissue which surrounds hyaline cartilage; contains fibroblasts and chondroblast precursors • Photomicrograph of perichondrium phagocytosis active engulfment by a cell of particles or another cell pericyte precursor of smooth muscle cells located in certain capillaries pharynx passage between the nasal and oral cavities and the larynx perikaryon the cell body of the neuron pigmented epithelium layer of the retina which prevents light scatter perilymph fluid between the bony and membranous labyrinth pituicyte cell of the neurohypophysis which may play a supportive role to the neurons located in that structure perimetrium 36 • Photomicrograph of pituicyte polychromatophilic erythrocyte small, basophilic, enucleated cell which is the immediate precursor of the erythrocyte • Photomicrograph of polychromatophilic erythrocyte plasma cell derivatives of B-lymphocytes which mass produce antibodies; eccentrically placed nucleus with round shape; the distinct pattern or heterochromatin frequently presents a "cartwheel" appearance; negative Golgi and basophilic cytoplasm are evident • Photomicrograph of plasma cell portal lobule triangular model of liver organization with three central veins surrounding a portal triad plasma membrane semipermeable bilayer which surrounds cells; consists of phospholipids, proteins and carbohydrates portal system of blood flow a system in which a vein or arteriole is interposed between two capillary beds; found in the kidney, liver, and piutitary platelet formed element of the blood involved in clotting • Photomicrograph of platelet portal triad branches of the hepatic artery, the portal vein, and the bile duct that run in tandem within the liver parenchyma plicae circularis semicircular folds within the submucosa of the small intestine; confer an irregular surface to the inner small intestine; most numerous in the jejunum portal vein a vessel that brings blood from the digestive tract, spleen, and pancreas to the liver • Photomicrograph of portal vein • Photomicrograph of portal vein podocyte cell of the visceral layer of Bowman's capsule; has numerous foot processes which act as part of the filtration barrier • Photomicrograph of podocyte postcapillary venule also known as high endothelial vessel (HEV); vessels with cuboidal lining in the deep cortex • Photomicrograph of HEV polar body body of excess cytoplasm produced in the meiotic division of the oocyte; eventually degenerate posterior chamber of eye space posterior to the iris and anterior to thelens posterior lobe see neurohypophysis polychromatophilic erythroblast cell that has cytoplasm that is a dull gray to gray-green color due to a combination of basophilic staining (polyribosomes) and eosinophilic staining (hemoglobin); continued division and maturation gives rise to normoblasts • Photomicrograph of polychromatophilic erythroblast primary center of ossification site of initial bone formation inside the diaphysis primary follicle see folliculogenesis 37 primary oocyte see folliculogenesis primordial follicle see folliculogenesis crease in number of granules and increase in cell size (24 um) as a result of one or more divisions, smaller late promyelocytes are produced • Photomicrograph of promyelocyte principal cell cell of the parathyroid which secretes parathyroid hormone (PTH) • Photomicrograph of principal cell prostate gland largest accessory sex gland; secretes acid phosphatase, fibrinolysin, and citric acid; contains prostatic glands procollagen polypeptide which is converted to collagen extracellularly prostatic concretion calcified aggregate of the prostate gland which has "tree ring" like appearance; found especially in older men proerythroblast earliest precursor of erythrocytes; has large nucleus and basophilic cytoplasm; 13-18 um in diameter; large spherical nucleus with 1-2 distinct nucleoli; thin rim of slight to moderate basophilic cytoplasm (basophilia attributable to increasing numbers of free ribosomes; rER absent); divides to give rise to basophilic erythroblast • Photomicrograph of proerythroblast prostatic gland tubuloalveolar gland that secretes acid phosphatase, citric acid, and fibrinolysin into the urethra prostatic sinus spaces that open into the prostatic urethra prostatic urethra the portion of the urethra within the prostate proliferative mammary gland mammary gland consisting of dense concentration of secretory structures • Photomicrograph of proliferative mammary gland proximal convoluted tubule tortuous tubule close in proximity to the glomerulus; the cuboidal cells of this structure exhibit a prominent brush border; most of sodium-potassium and water reabsorption occur here • Photomicrograph of proximal convoluted tubule • Photomicrograph of proximal convoluted tubule proliferative phase of the endometrium see endometrium promonocyte precursor of the monocyte; large cell with a slightly indented nucleus and basophilic cytoplasm proximal straight tubule tubule of the medullary ray; lined by cuboidal cells with weak brush borders • Photomicrograph of PST promyelocyte also known as "progranulocyte"; large cell which is the earliest precursor of the granulocytes; has slightly indented nucleus and distinct nucleolus; 16 um in diameter; characterized by cytoplasmic azurophilic granules; during maturation there is an in- pseudostratified columnar epithelium unilayer of columnar cells, all of whose apices do not contact the lumen; the lining of the trachea, bronchi, ductus deferens, 38 and ductus epididymis; suited for secretion, absorption, or duct-lining • Photomicrograph of pseudostratified columnar epithelium • Photomicrograph of pseudostratified ciliated columnar cell R pulmonary artery vessel that brings deoxygenated blood to the lungs • Photomicrograph of pulmonary artery red blood cell an erythrocyte; biconcave-shaped, enucleated cell responsible for oxygen delivery and carbon dioxide removal • Photomicrograph of erythrocyte pulmonary vein vessel that brings oxygen rich blood from the lungs to the heart; lined with cardiac muscle • Photomicrograph of pulmonary vein red margin area of the oral surface of the lip which is thin and rich in blood vessels red pulp part of the spleen rich in red blood cells; these are filtered and removed here (if damaged) • Photomicrograph of red pulp • Photomicrograph of red pulp Purkinje fiber large, eosinophilic cells with prominent nuclei specialized for conduction of electrical signals in the heart; allows for rhythmicity of heartbeat • Photomicrograph of Purkinje fiber Reissner's membrane see vestibular membrane pyknotic nucleus a condensed nucleus; forms as a prelude to apoptosis releasing factor hormone of the hypothalamus which stimulates secretion by the adenohypophysis pyloric gland gland of the stomach pylorus (region which meets the duodenum); branched, tubular glands containing mostly mucous surface cells and some parietal and APUD cells renal calyx see minor calyx pyramid cone-shaped structure which houses the tubular networks of the numerous nephrons of the kidney parencyma renal corpuscle the combination of Bowman's capsule and the glomerulus renal column cortical tissue in between two adjacent pyramids renal lobule a segment of a renal lobe; the lobe consists of a pyramid and its surrounding connective tissue residual body 39 1)see lysosome 2)excess cytoplasm shed by the late spermatid work for various tissues • Photomicrograph of reticular fiber reticulocyte same as polychromatophilic erythrocyte resorption canal a "tunnel" carved by osteoclasts advancing through bony matrix during bone remodeling retina structure within the eye responsible for photoreception; consists of several layers (outer to inner): • pigmented epithelium • layer of rods and cones • outer limiting membrane • outer nuclear layer • outer plexiform layer • inner nuclear layer • inner plexiform layer • ganglion cell layer • optic nerve fiber layer • inner limiting membrane respiratory bronchiole see bronchiole respiratory epithelium epithelium of the respiratory portion of the bronchial tree respiratory portion the structures of the respiratory system that function in gas exchange; these include: • respiratory bronchioles • alveolar duct • alveolar sac • alveoli ribosome cellular structure responsible for translating mRNA message into protein product resting mammary gland same as inactive mammary gland rod photoreceptor of the retina responsible for black/white vision rete testis channel lined with simple cuboidal epithelium that extends from the tubuli recti • Photomicrograph of rete testis Rokitansky-Aschoff sinus invagination of the gallbladder mucosa that allows for bacterial aggregation, and hence infection reticular cell 1)this stellate cell has long processes usually attached to the reticular fibers; the processes cover "reticular fibers" which are the collagenous stroma of the lymph node 2)"adventitial cell"; may function as antigen-presenting cell 3)cell of the bone marrow which provides support for developing blood cells • Photomicrograph of reticular cell rough endoplasmic reticulum (rER) long, winding organelle which is studded with ribosomes involved in producing proteins bound for secretion or plasma membrane integration ruffled border extensions of the membrane of the osteoclast involved in resorption of bony matrix rugae longitudinal folds of the inner stomach reticular fiber connective tissue element composed of collagen III; provides supporting frame40 • Photomicrograph of scala vestibuli Schmidt-Lantermann cleft space within the myelin sheath containing Schwann cell cytoplasm • Photomicrograph of S-L cleft S Schwann cell supporting cell of the peripheral nervous system; forms the myelin sheath • Photomicrograph of Schwann cell sarcolemma plasma membrane of myofibers sclera opaque layer of dense connective tissue covering the eye around the cornea sarcomere banded arrangement of myofilaments which is the basic contractile unit in striated muscle sebaceous gland gland of the epidermis that secretes an oily coat which provides barrier and bacteriostatic function • Photomicrograph of sebaceous gland sarcoplasm cytoplasm of muscle cells sarcoplasmic reticulum smooth endoplasmic reticulum (sER) of skeletal, cardiac, and visceral striated muscle (i.e. pharynx, tongue, and diaphragm) especially suited for sequestration/release of calcium sebaceous gland of Zeis oil gland associated with eyelashes secondary center of ossification center of bone deposition after birth; located in the upper epiphysis satellite cell 1)cell that gives rise to new muscle cells upon injury to muscle tissue 2)supporting cell of nerve cell bodies located in ganglia • Photomicrograph of satellite cell secondary follicle see folliculogenesis secretory phase of the endometrium see endometrium scala media middle compartment of the cochlear canal; houses the basilar membrane and organ of Corti • Photomicrograph of scala media secretory vesicle bud from the trans Golgi containing proteins bound for secretion seminal colliculus pyramid-shaped region between the prostatic sinuses scala tympani lowest compartment of the cochlear canal • Photomicrograph of scala tympani seminiferous tubule highly tortuous structure within which male germ cells begin development scala vestibuli uppermost compartment of the cochlear canal 41 septa connective tissue within the parenchyma of an organ (i.e. thymus, in which septa emerge from the capsule into the parenchyma) simple squamous epithelium a single layer of squamous cells; found in lining of body cavities, blood vessels, respiratory surfaces, and kidney elements; ideal for both barrier and gas exchange function serosa a mesothelium and its underlying connective tissue sinusoid see sinusoidal capillaries serous acinus circular arrangement of serous-secreting cells sinusoidal capillary capillary whose basement membrane is not fully adjoined and whose endothelial cells maintain an intercellular distance; found in liver, spleen, and bone marrow • Photomicrograph of sinusoid • Photomicrograph of sinusoidal capillary serous cell cell that secretes a watery fluid serous demilune a half moon-shaped structure attached to a mucus gland which produces serous secretions sinusoidal lining cell endothelial cells which line sinusoids of the bone marrow serous gland a gland whose secretions are watery rather than organic skeletal muscle voluntary, striated muscle which allows for body movement via rapid contractions; the striations result from the banded pattern of the sarcomere • Photomicrograph of skeletal muscle serous-secreting cell see serous cell Sertoli cell columnar cells within the seminiferous tubule; nourishes the developing germ cell and protects them from antibodies by forming the blood-testis barrier; also phagocytoses residual bodies • Photomicrograph of Sertoli cell slit membrane thin membrane covering the slit pores; influences filtration slit pore space between the foot processes of podocytes simple columnar epithelium a single layer of columnar cells typically lining the digestive system; ideal for absorption small granule cell APUD cell of the respiratory epithelium simple cuboidal epithelium a single layer of cuboidal cells typically lining ducts (i.e. exocrine ducts, kidney tubules, etc.) • Photomicrograph of simple cuboidal epithelium smooth endoplasmic reticulum (sER) tubular organelle involved in: • lipid metabolism • glycogen metabolism • membrane formation 42 the process of spermatocyte formation; occurs in the seminiferous tubule smooth muscle involuntary, non-striated muscle; allows for slow, prolonged contraction • Photomicrograph of smooth muscle • Photomicrograph of smooth muscle spermatogenesis the process of spermatozoan development from spermatogonia; occurs in the seminiferous tubule smooth muscle cell cell which resides in and secretes the matrix of smooth muscle; communicates with other smooth muscle cells via gap junctions • Photomicrograph of smooth muscle cell spermatogonium diploid stem cell of the male germ line • Photomicrograph of spermatogonia spermatozoan male germ cells; equipped with flagella which allows it to travel to oocyte for fertilization somatotrope acidophilic cell of the adenohypophysis which produces growth hormone (GH) spermiogenesis the development of spermatids into fully mature spermatozoa; begins in the seminiferous tubule and continues through the epididymis space of Disse space between the basal surfaces of the hepatocytes and the basal surfaces of endothelial cells and Kupffer cells; region of hepatocyte-blood exchange; also houses the lipocytes • Photomicrograph of space of Disse sphincter pupillae muscle muscle of the iris which constricts the pupil specific granule container for antibacterial agents, such as lysozyme; present in the granulocytes spiral artery vessel of the uterine lining which undergoes structural changes during the menstrual cycle; see endometrium sperm same as spermatozoa spiral ganglion group of nerve cell bodies located in the modiolus; responsible for auditory reception • Photomicrograph of spiral ganglion spermatid see early and late spermatid spermatocyte • primary spermatocyte- cell that is the immediate mitotic descendant of the spermatagonium; contains 4n DNA content due to S phase DNA synthesis • secondary spermatocyte- cell produced from the first meiotic division of the primary spermatocyte • Photomicrograph of spermatocyte spiral ligament structure located along the lateral cochlear wall; it is a thickening of the periosteum in that region • Photomicrograph of spiral ligament splenic cord component of the spleen which consists of reticular cells, macrophages, lymphocytes, and granulocytes; located in the red pulp spermatocytogenesis 43 • • Photomicrograph of splenic cord Photomicrograph of splenic cord exocrine glands; serves well as barrier and conduit (duct-lining) • Photomicrograph of st. cub. epithelium splenic nodule areas of the splenic white pulp housing Blymphocytes stratified squamous epithelium multilayer of squamous cells; lining of oral cavity, esophagus, epidermis, and vagina; serves as a barrier and protective layer splenic sinus areas between splenic cords; located in the red pulp spongy bone also known as "cancellous bone"; bone consisting of many trabecular formations; houses much blood supply stratified squamous keratinized epithelium see epidermis stratified squamous non-keratinized epithelium the lining of the vagina and the oral surface of the lip spongy urethra the part of the urethra within the penis squamocolumnar junction area which is a transition between the stratified squamous epithelium of the exocervix and the simple columnar epithelium of the endocervix; the area where the former epithelium overtakes the latter is known as the transformation zone • Photomicrograph of squamocolumnar junction stratum basalis 1) see 2) see endometrium epidermis stratum corneum see epidermis stratum functionalis see endometrium squamous cell a cell whose width dimension is greater than its height stratum granulosum see epidermis stem cell any cell that serves as a precursor for another, i.e. the basal cell of epithelia stratum lucidum see epidermis stratum spinosum see epidermis stereocilium unusually long microvilli present only in the epididymis and hair cells of the ear stria vascularis located on lateral cochlear wall; site of endolymph synthesis • Photomicrograph of stria vascularis stratified columnar epithelium a multilayer of columnar epithelial cells; serves well as a barrier or in duct-lining striated border the brush border of the intestines • Photomicrograph of striated border stratified cuboidal epithelium multilayer of cuboidal cells that lines sweat glands and ducts and some ducts of 44 striated duct same as intralobular duct phospholipid released by type II pneumocytes which prevents collapse of the alveolus stroma the supporting tissue of an organ; consists of various connective tissue elements; see also parenchyma suspensory ligament fiber connecting the lens to the ciliary body; allow for ciliary muscle control of the lens subcapsular sinus see cortical sinus sustentacular cell columnar cell that provides nutritional support to olfactory cells subendothelial layer of connective tissue 1) layer beneath the endocardium; houses the conduction system of the heart 2) inner layer of the tunica intima synapse space between an axon and its target (neurons or effector cells) sublingual gland gland located in the floor of the mouth; most are mucous glands some of which house serous demilunes • Photomicrograph of sublingual gland syncytiotrophoblast part of the trophoblast of the blastocyst; multinucleate layer that embeds into the endometrium • Photomicrograph of syncytiotrophoblast submandibular gland gland located on either side of the floor of the mouth; are mostly serous glands and some mucous glands • Photomicrograph of submandibular gland T submucosa a stabilizing layer of dense irregular connective tissue below the mucosa; provides resistance to shearing forces subpericardial adipose tissue grouping of adipocytes beneath the pericardium T tubule internal extension of the plasma membrane in skeletal and cardiac muscle cells which allow for rapid calcium entry (necessary for contraction) supporting cell same as sustentacular cell tarsal gland also known as Meibomian glands; long sebaceous glands of the tarsal plates suppressor T-lymphocyte a cell which suppresses B-lymphocytes activity to prevent a hyperimmune response tarsal plate flexible support of the eyelid; consists of dense fibrous and elastic tissue surfactant 45 territorial matrix proteoglycan-rich matrix directly adjacent to the lacuna of a chondrocyte (or isogenous group) taste bud specialized group of cells within the papillae of the dorsal tongue; allow for various forms of taste • Photomicrograph of taste bud testosterone see Leydig cells tectorial membrane structure overlying the organ of Corti which is involved in producing a shearing effect on the hair cells upon vibration; this process stimulates the hair cells, leading to sound perception theca externa outer layer of connective tissue surrounding the growing follicle; contains many smooth muscle cells • Photomicrograph of theca externa • Photomicrograph of theca externa cell tendinocyte elongated cell with invisible cytoplasm and flattened, poorly-stained, nucleus; appears in the tendon and is positioned in a very regular pattern of rows between parallel bundles of collagen fibers; makes fibers and ground substance of the tendon • Photomicrograph of tendinocyte theca interna inner layer of the connective tissue sheath surrounding the maturing follicle; highly vascularized; secrete androgens that are converted by granulosa cells to estrogen • Photomicrograph of theca interna • Photomicrograph of theca interna cell tendon dense regular connective tissue which joins muscle to bone • Photomicrograph of tendon theca lutein cell cell of the corpus luteum derived from the theca interna • Photomicrograph of theca lutein cell teniae coli smooth muscle bands on the outer surface of the colon (large intestine); three of these strips can be seen macroscopically • Photomicrograph of teniae coli thick filament see myosin terminal bar light microscopy term for the junctional complex • Photomicrograph of terminal bar thin filament see actin thin segment the thin, bottom portion of the loop of Henle • Photomicrograph of thin segment terminal bronchiole see bronchiole terminal web a horizontal network of actin filaments that crosses with the vertical microvillar actin filaments to grant support, and perhaps contractile ability thrombopoiesis the process of clot formation thymus cortex see cortex 46 thymus medulla see medulla transitional epithelium cellular layer capable of undergoing a change in its property (i.e. shape of dome cells of the bladder) • Photomicrograph of transitional epithelium thyroid gland produces triiodothyronine and thyroxine which are responsible for aspects of metabolism, growth, etc. thyrotrope acidophilic cell of the adenohypophysis; produces thyrotropic hormone (TSH) tropocollagen another name for the collagen molecule tropomyosin double helix protein which covers myosinbinding sites on actin filaments tissue a group of cells with a common structure and function(s) troponin protein which is connected to tropomyosin and along with it, block the myosinbinding site on the actin filament tissue absorptive cell see absorptive cell T-lymphocyte see lymphocyte tubuli recti small channels leading away from the seminiferous tubules; lined only by Sertoli cells • Photomicrograph of tubuli recti trabeculum 1) connected spicules which form a meshwork in spongy bone 2) connective tissue that extends from the capsule into the substance of the lymph node or spleen; houses various vessels, including the trabecular artery and vein • Photomicrograph of trabecular vein tunica adventitia connective tissue tissue layer on the outside of arteries and veins which houses nerves, vessels, and much adipose • Photomicrograph of tunica adventitia • Photomicrograph of tunica adventitia trabeculum of spleen see trabeculae trabecular artery see trabeculae tunica albuginea 1)thick outer connective tissue covering of the testis 2)a dense fibroelastic sheath surrounding the erectile tissue of the penis 3)dense connective tissue layer located beneath the germinal epithelium of the ovary trabecular vein see trabeculae trachea air conducting tube which branches into the left and right bronchi; the bronchi further divide into secondary and tertiary bronchi, and bronchioles, in that order tunica intima innermost layer of vessels; consists of the endothelium and a subendothelial layer of connective tissue transformation zone see squamocolumnar junction 47 • with the proximal convoluted tubule • Photomicrograph of urinary pole Photomicrograph of tunica intima tunica media intermediate layer of vessels; has much smooth muscle and connective tissue • Photomicrograph of tunica media • Photomicrograph of tunica media urinary space space between the visceral and parietal layers of Bowman's capsule; site of filtrate delivery • Photomicrograph of urinary space type I pneumocyte squamous cell that lines most of the alveolar surface • Photomicrograph of type I pneumocyte uterine discharge menstrual flow; composed of epithelial cells and blood uterine gland glands of the uterine mucosa; see endometrium type II pneumocyte cuboidal cell that is part of the alveolar lining; secretes surfactant • Photomicrograph of type II pneumocyte uterine stroma see stroma uterus female reproductive organ which houses and supports the developing embryo • Photomicrograph of uterus U VWZ umbilical artery maternal vessel whose branches pass into the villi and exchange material with the fetal circulation vagina fibromuscular tube opening into the cervix; lined with stratified squamous epithelium unmyelinated axon those lacking a myelin sheath; are relatively slow in conduction • Photomicrograph of unmyelinated nerve valve a structure within blood and lymph vessels that prevents backflow urethra a channel originating in the bladder that delivers semen and urine through the penis vasa recta the vessels that supply and exchange substances with the tubular network of a juxtamedullary nephron urinary pole of the renal corpuscle the pole of the renal corpuscle continuous 48 • Photomicrograph of intestinal villus 2) see chorionic villus vasa vasorum blood supply located in the tunica adventitia visceral pleura see serosa vascular pole of renal corpuscle the entry/exit point of the afferent arteriole and efferent arteriole, respectively, from the renal corpuscle vitreous cavity space containing the vitreous humor of the eye • Photomicrograph of vitreous body vascular space opening within erectile tissue lined by endothelial cells; allows for profuse blood flow during erection vitreous humor gel-like substance that fills the posterior portion of the eye; gives the eye its shape vein vessel which carries oxygen-poor blood away from tissues to the heart • Photomicrograph of a large vein vocal fold two folds of musoca within the larynx; vibrations of these folds produce sound pitch venous sinus venous channel of the cranial cavity lined with endothelial cells • Photomicrograph of venous sinus Volkmann's canal channel which allows passage of blood vessels and nerves from the periosteal layer to the Haversian canals • Photomicrograph of Volkmann's canal ventricular fold mucosal fold of the larynx located above the vocal folds; important in resonance von Ebner's gland serous gland at the base of papillae that wash away food particles • Photomicrograph of von Ebner's gland venule small vessel carrying deoxygenated blood; located between a capillary and a small vein • Photomicrograph of venule • Photomicrograph of venule wandering cell a cell that can travels distances to execute their function; i.e. lymphocytes, granulocytes, and monocytes vessel see blood vessel vestibular membrane also known as "Reissner's membrane"; the upper wall of the scala media • Photomicrograph of vestibular membrane white blood cell a cell of the immune system; known also as leukocyte white pulp area of the spleen rich in lymphocytes • Photomicrograph of white pulp • Photomicrograph of white pulp villus 1) finger-like extension of the mucosa of the small intestine 49 Z line see Z-disk zone of hypertrophy layer of massive chondrocytes containing large stores of glycogen • Photomicrograph of zone of hypertrophy Z-disk anchoring area for actin filaments in the sarcomere • Photomicrograph of Z-disk zone of proliferation layer of large chondrocytes undergoing active growth and division • Photomicrograph of zone of proliferation zona fasciculata middle zone of the adrenal cortex composed of cord-like arrangement of cells; site of glucocorticoid production; glucocorticoids function in: • conversion of amino acids to glucose • fatty acid breakdown • catabolism of fatty acids and amino acids • suppression of inflammation • Photomicrograph of zona fasiculata zone of reserve cartilage layer of little cellular growth or matrix production • Photomicrograph of zone of reserve cartilage zone of resorption layer closest to shaft of bone; cartilage is actively digested by osteoclasts here • Photomicrograph of zone of resorption zona glomerulosa outer zone of the adrenal cortex; cells here secrete mineralocorticoids (i.e. aldosterone), which function in the resorption of sodium at the expense of potassium • Photomicrograph of zona glomerulosa zonula adherens relatively weak band-like intercellular adhesion on lateral cell surface zona pellucida acidophilic layer between the oocyte and adjacent follicular cells; first appears in the primary follicle • Photomicrograph of zona pellucida zonula occludens lateral surface cellular adhesion which serves as a diffusion barrier zymogen granule acidophilic granule containing secretory products in their inactive forms, i.e. granules of the pancreatic acinar cells contain trysinogen, chymotrypsinogen, etc. zona reticularis the innermost zone of the adrenal cortex; produces weak androgens and some glucocorticoids • Photomicrograph of zona reticularis zone of calcified cartilage layer where chondrocytes degenerate due to calcification of matrix; see calcified cartilage • Photomicrograph of zone of calcified cartilage 50 51 52