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Histology What to look for Histology review Quiz = 40 pts • Some slides set up • Some pictures on the projector Questions: • What kind of tissue? • General function? (e.g. absorption, protection) • Cells, fibers, ground? • An example of where would you find it? Slides • Epithelial tissues (7 types, could be ANY of the examples provides) • Connective tissues (11 types, ANY example that we looked at) • Integument and accessory structures Epithelial tissue Let’s review…. Simple cuboidal epithelium • lining a tubule (longitudinal cut). Some of the cell boundaries between "blocks" or "cubes" here are quite distinct. Simple Cuboidal • Covers surface of ovary, lines kidney tubules and small ducts of glands (thyroid and pancreas) Tubule - cross section simple cuboidal Another example - kidney Type? Simple squamous epithelium • High power view of endothelial cells lining a small blood vessel cut in cross-section. (You see just the nuclei - the cytoplasm between them is extremely flat.) Endothelium = the simple squamous epithelium lining blood vessels. Simple squamous epithelium Kidney Superficial view (squamous) Type? Simple columnar • Another example – intestine, with goblet Intestinal lining Yet another Type? Pseudostratified ciliated columnar epithelium Trachea. Nuclei are at different levels. All cells touch the basement membrane, but only the taller cells reach the lumen. The cilia are longer and less regular than the microvilli of a striated border. Pseudostratified Columnar Epithelium • Look like multiple layers • Trachea Figure 4–5b Another example Cilia – surface view Type? Bladder Low power Transitional Epithelium • Tolerates stretching • Appearance changes (stratified to simple) • Urinary bladder Figure 4–4c Type? Stratified Squamous Epithelium Figure 4–3b Example Example Type? Type? Stratified Cuboidal Epithelium • Sweat gland ducts Figure 4–4b Type? Stratified Columnar Epithelium • Rare • Salivary gland duct Figure 4–5c Connective tissue Connective tissues Connective tissue proper • Loose connective tissue – Areolar – Adipose – Reticular • Dense connective tissue – Dense regular – Dense irregular – Elastic tissue Fluid CT –Blood Supporting CTs •Cartilage –Hyaline cartilage –Elastic cartilage –Fibrocartilage • Bone Areolar tissue • A loose CTP Areolar Areolar: what to look for • • • • Fibroblasts Collagen fibers Elastic fibers Mast cells and macrophages • Found? Throughout body, under dermis, divides skin from underlying tissues Fibroblasts • Resting fibroblasts typically have so little cytoplasm that the cells appear, by light microscopy, as "naked" nuclei Fibroblast Adipose tissue • Another lose CTP (note nucleus) Adipose: what to look for • Lots of cytoplasm • Slim nuclei pushed off the side • Found? You know where Reticular tissue • The third type of loose CTP Reticular tissue Reticular: what to look for • Reticular fibers (network) • Found? Internal framework in many sort organs (liver, spleen) supporting the parenchyma Dense CTP • Dense regular – strength in one direction • Dense irregular – strength in all directions • Elastic tissue - pliable Dense regular Dense regular: what to look for • Thick parallel bundles of collagen • Small fibroblasts in between bundles • Found? Tendons, ligaments, deep fascia. Dense irregular More dense irregular Dense irregular: what to look for • Mesh of collagen fibers (irregular looking) • Interspersed fibroblasts • Found? Dermis of skin, periosteum, perichondrium Elastic tissue Elastic tissue: what to look for • Elastic fibers (instead of collagen fibers) in large bundles • Fibroblasts • Found? Between vertebrae, in blood vessel walls (underneath endothelium) Fluid CT • Blood Blood: what to look for • RBCs • White blood cells (darker): monocytes, lymphocytes, granulocytes • Platelets Supportive CT • Cartilage – gelatinous, padding – Hyaline cartilage – Elastic cartilage – Fibrocartilage Hyaline cartilage • Glasslike because fibers not visible More hyaline • There are collagenous and elastic fibers lying in the cartilage matrix but they are invisible because their “refractive index” is the same as that of the matrix (like cornea) More hyaline Hyaline cartilage Hyaline • Hyaline cartilage (lavender matrix), with perichondrium (pink) outside it. The latter is a dense regular collagenous CT. Cartilage cells = chondrocytes, and they are lying in the lacunae. Hyaline cart.: what to look for • Perichondrium • Chondroblasts (make the matrix fibers and ground) • Chondrocytes and lacunae • Where? Most joints, nasal septum Elastic cartilage Elastic cart: what to look for • • • • Many elastic fibers in matrix Perichondrium Chondroblasts Chondrocytes in lacunae Fibrocartilage Fibrocartilage: what to look for • Irregular, wispy collagen fibers • Chondrocytes, often stacked up • Found? Intervertabral discs of spine, pads in knee joint Supportive CT: Bone • Detail of lacuna, showing radiating canaliculi. Tissue fluid from the capillaries and connective tissue of the Haversian canal can seep through these spaces and channels, bringing nutrients to the stellate osteocytes residing there. Bone: what to look for • • • • • • Osteon (whole circular structure) Concentric lamellae (of matrix) Central canal (at center of lamellae) Osteoblasts Osteocytes in lacunae Canaliculi Found? Bones! Integument Epidermis and dermis Epidermis What to look for: • Usually darkest between stratum germinativum and stratum granulosm (granulosm often a dark meandering line) • Keratinized cells often lift off the section • Melanocytes just below basal lamina Dermis: Papillary vs. Reticular layer What to look for: • Papillary layer – has ridges – is areolar – Just under basal lamina • Reticular layer – much thicker – Dense irregular CT Again Merocrine sweat glands Merocrine sweat gland • What to look for: – Found in most skin – Coiled, tubular – Small lumens in cross section – Have duct that goes all the way to the epidermal surface and ends in sweat pore – Smaller than apocrine, don’t extend as deep into dermis Apocrine sweat gland Apocrine sweat gland What to look for: • Associated with hair follicle • Only in nipples, groin, armpit • Large lumens • Deeper in dermis than merocrine Hair with sebaceous glands and arrector pilli Hair What to look for: • Follicles are rarely complete • Can often see root, papilla (at base, wher hair grows) • Arrector pilli muscle at an angle • Associated glands (which are?) Sebaceous glands Sebaceous glands What to look for: • Associated with hair follicle • Found most everywhere hair follicles are found in skin • Look like cauliflower (maybe?) Sebaceous follicle Sebaceous follicle What to look for: • Also look like cauliflower • Found on face and trunk only • NOT associated with hair follicle • Have duct that opens onto skin surface