Download Histology

Bio. 2304 - Human Anatomy –
HISTOLOGY (STUDY OF TISSUES) - Lab & Lecture Objectives
Important:
¾ For each slide know
1.) specific tissue type
2.) any specialized structures or cells in the tissue (& know their functions)
3.) tissue locations
4.) tissue functions.
¾ Don’t forget that cells are mainly composed of water and are very translucent! Turn down the light to see
more detail!
¾ Look at each slide under the indicated magnifications; l. p. = low power; h. p. = high power
¾ Make drawings of each tissue type. Make sure that you bring some colored pencils to this lab!
I. EPITHELIAL TISSUE - covers body surfaces (internal and external); lines body cavities & tubes; forms glands.
Note: Epithelial tissue can be classified on the basis of the arrangement of the cells: simple (one cell layer
thick), stratified (more than one cell layer thick), or pseudostratified (cells are staggered giving the false
appearance of being stratified). Characteristics of epithelium:
¾ cells fit closely together
¾ cells are attached to an adhesive basement membrane (glycoproteins and connective tissue)
¾ the tissue is avascular (no blood supply – it receives nutrients by diffusion from blood vessels in the
underlying connective tissue).
¾ cells can have microvilli or cilia on their surfaces.
¾ tissue has high regenerative ability
¾ Endothelium (inner covering)– epithelium that provides a slick lining in lymphatic vessels, blood vessels, and
heart.
¾ Mesothelium (middle covering) – epithelium found in serous membranes lining the ventral body cavity and
covering its organs; also called a serous membrane or serosa.
A. Squamous Epithelium
1. Simple Squamous Epithelium
Description: flat, scalelike, irregularly shaped cells (like fried eggs)
Location: air sacs of lungs; nephrons of kidney; lining of circulatory system, lymphatic vessels, & ventral
body cavity
Fxns: diffusion (gas exchange) in lungs, filtration in kidneys (why cells are so thin)
Slide: “Mammal Lung Sec. 31-5648 (H2460)” (l.p.); be careful not to confuse with adipose tissue
2. Stratified Squamous Epithelium
Description: composed of many layers of squamous epithelial cells
Location: nonkeratinized type in moist linings of the esophagus, mouth, & vagina; keratinized type forms
the epidermis of the skin (we’ll talk more about the protein keratin in the integumentary system)
Fxns: protects underlying tissues in areas subjected to abrasion
Slides:
a. "Stratified Squamous Epithelium Human (H6014)" (l. p.) - look at the outer layer of the tissue section
for the strat. squamous cells; this is a slide of the esophagus.
b. “Squamous Epithelium Smear, Human Mouth (H15)” (l.p.) - The squamous epithelial cells in your
cheek are stratified, but the cells separated when they made the slide, so you will see individual cells;
notice how thin and scalelike they appear; each cell has a small round nucleus.
B. Cuboidal epithelium
Description: cube shape; have spherical nuclei
Location: kidney tubules, small glands, surface of ovary
Fxns: secretion (ex. tears, saliva) & absorption (ex. reabsorption of H2O in kidneys)
Slide: "Simple Cuboidal Epithelium (93 W3024)" (h. p.) - look at cells lining tubes (large, long spaces)
C. Columnar epithelium
Description: long, column shaped; oval nuclei; some have cilia (hair-like processes; in respiratory tract, cilia whip
up mucous to trap bacteria, etc.); cells in digestive tract have microvilli on surface (folded cell membranes to
provide more surface area for absorption); this tissue may also contain mucous secreting goblet cells.
Location: nonciliated type lines digestive tract, gall bladder, and excretory ducts of some glands; ciliated type lines
respiratory tract and fallopian tubes
Fxns: secretion of mucous, enzymes; absorption; ciliated type propels mucous (in the respiratory system) and
eggs (in the reproductive system).
Slide: "Goblet Cell Epithelium (H215)" (h. p.) - on this slide columnar epithelial cells line the villi of the intestine
(fingerlike structures that project in the lumen of the intestine to increase its surface area for more absorption); id.
villus, goblet cells (interspersed among the columnar epithelial cells & are white to very light purple in color - if
you look closely, you can actually see the mucous coming out of some of the cells), & columnar epithelial cells.
II. CONNECTIVE TISSUE - protects & supports the body & its organs, binds organs together, & stores
energy reserves. Extracellular matrix is produced by connective tissue cells. Connective tissue cells have
different names depending on the type (ex. fibroblasts, chondrocytes, osteocytes, adipocytes, etc.). The matrix is
composed of :
1.) ground substance - may be liquid, semisolid, of hard (when hard the cells reside in cavities in the matrix
called lacunae); made up of glycoproteins and polysaccharides; matrix supports cells, binds them
together, and gives strength & elasticity to tissues; it also holds fluid.
2.) fibers: collagenic (protein collagen, tough, white), elastic (protein elastin, yellow) , and reticular (fine,
collagenic fibers with a coating of glycoprotein); fibers provide support, strength, and elasticity.
A. Loose Connective Tissue (loose arrangement of fibers in the matrix)
1. Areolar (“bubble wrap”)
Description: gel-like matrix; contains all 3 fiber types, fibroblasts (produce new fibers & matrix), and white
blood cells.
Location: under epithelia (ex. lamina propria of mucous membranes) and around organs & capillaries
Fxns: like bubble wrap - wraps & cushions organs
Slide: "(H105) Areolar Tissue Spread Verhoeff, w.m." (h. p.)
2. Reticular
Description: loose ground substance, reticular fibers, fibroblasts called reticular cells; also contains
white blood cells
Location: in lymphoid organs (lymph nodes, bone marrow, spleen)
Fxns: support; in lymph nodes, the fibers trap bacteria.
Slide: "Human Reticular Tissue sec. 31-2674 (H6252)" (h. p.) (reticular fibers stain very dark)
3. Adipose
Description: sparse, gel-like matrix; adipocytes (fat cells) have nucleus & cytoplasm pushed to the side
by large fat droplet.
Location: under skin, around kidneys, eyeballs, and other organs, in bones (yellow marrow) and breasts,
and within abdomen.
Fxns: energy storage, insulation, supports & protects organs
Slide: "Adipose Tissue Fat Stained, w.m." (l. p.) - lipid material inside the adipocytes has been stained
red; the cytoplasm has been pushed to the sides of the cells and has been stained purple; you can also
see adipose cells that are not stained red (the lipid is gone and you see a white space inside the cell)
B. Dense Connective Tissue
1. Dense regular connective tissue (fibers run in same direction)
Description: primarily parallel collagen fibers; a few elastic fibers; mostly fibroblasts
Location: tendons, most ligaments
Fxns: tendons attach muscles to bones or to muscles, ligaments attach bones to bones; withstands
tension exerted in one direction.
Slide: to be determined by lab instructor
2. Dense irregular connective tissue (fibers are arranged irregularly)
Description: irregularly arranged collagen fibers; some elastic fibers; mostly fibroblasts
Location: dermis of skin, submucosa of digestive tract, fibrous joint capsules
Fxns: provides structural strength; withstands tension exerted in many directions
Slide: to be determined by lab instructor
C. Cartilage - capable of enduring more stress than connective tissues just discussed; unlike other connective
tissues, cartilage is avascular and contains no nerves; its strength is due to collagen & elastic fibers; matrix is
composed of chondroitin sulfate, hyaluronic acid, and lots of water; chondroblasts produce matrix & when
mature (then called chondrocytes), these cells lie in spaces called lacunae.
1. Hyaline cartilage (“gristle”)
Description: firm matrix, fibers not detectable, and chondrocytes clearly visible
Location: forms most of embryonic skeleton; covers ends of long bones in joint cavities; forms costal
cartilages of ribs; nose; trachea; larynx
Fxns: support & reinforcement, cushions, resists compressive stress
Slide: "Hyaline Cartilage Trachea Human" (l. p.) - id. matrix and chondrocytes
2. Elastic cartilage
Description: similar to hyaline, but more elastic fibers
Location: external ear, epiglottis ("lid" on top of larynx - prevents food from entering windpipe), eustachian
tubes (equalize pressure in middle ear)
Fxns: maintains shape while allowing great flexibility
Slide: to be determined by lab instructor
3. Fibrocartilage
Description: matrix less firm than hyaline cartilage; mostly thick collagen fibers
Location: intervertebral discs, pubic symphysis (between hip bones), knee joint
Fxns: tensile strength with ability to absorb compressive shock
Slide: to be determined by lab instructor
D. Osseous (Bone) (2 types of bone tissue: compact & spongy)
Description: hard, calcified matrix; collagen fibers; osteocytes lie in lacunae; tissue is well-vascularized (lots of
blood vessels); basic unit of organization in compact bone is the osteon; spongy bone will be discussed later
under skeletal system.
Each osteon consists of:
¾ osteocytes (mature bone cells)
¾ lacunae (small spaces between lamellae that contain osteocytes)
¾ lamellae (rings of hard matrix - look like the growth rings of a tree!)
¾ canaliculi (minute canals that project from lacunae and provide numerous routes for nutrients to reach
osteocytes and for wastes to be removed from them)
¾ a central haversian canal (contains blood vessels and nerves); each osteocyte and its canaliculi look like a
spider.
Fxns: support; protection; provides levers for muscles to act on; stores calcium, other minerals; yellow marrow
stores lipids for energy; red marrow is the site for blood cell formation (hematopoiesis)
Slide: "(H155) Bone, c. s., Human, Ground" or “Ground Bone Compact Extra Thin (c.s. 71883”(l. p. & h. p.) - this
slide is of compact bone (not the spongy bone found in red & yellow bone marrow); id. osteon, osteocytes in
lacunae, haversian canal, canaliculi
E. Vascular (Blood)
Description: erythrocytes (red blood cells), leukocytes (white blood cells), & platelets in a liquid, straw-colored
matrix (plasma)
Location: liquid within blood vessels
Fxns: rbc's - transport of oxygen to cells and carbon dioxide away from them; wbc's – phagocytosis, immunity, &
allergic reactions; platelets - blood clotting; plasma - transports nutrients, enzymes, hormones, ions, carbon
dioxide, etc.
Slide: “Human Blood Smear Wright” (h.p.) - id. erythrocytes (red blood cells - no nucleus, biconcave discs),
leucocytes (white blood cells - large, stained purple, nuclei have different shapes); we'll id. thrombocytes
(platelets) on oil immersion later on in the semester when we study the cardiovascular system (platelets are cell
fragments involved in clotting).
III. MUSCLE TISSUE - Muscle tissue is highly specialized to contract.
A. Skeletal muscle
Description: long, cylindrical, multinucleated cells; obvious striations
Location: attached to bones or occasionally to skin
Fxns: voluntary movement (it's attached to bones - it makes bones move!), maintenance of posture, heat
production (heat is released from all of the chemical reactions taking place during contraction of the muscle)
Slide: "Skeletal Muscle - Monkey, l.s. (H9082)" (h. p.)
B. Cardiac muscle
Description: branching, striated, generally uninucleated cells that interdigitate at specialized junctions called
intercalated discs (these discs allow the muscle to contract as a unit) (under involuntary control)
Location: walls of the heart
Fxns: contraction propels blood into circulation
Slide: "Intercalated discs sec. H1790" (h. p.) - id. intercalated discs - very faint!; you may have to turn the slide
to vertical because they placed the tissue on the slide in the wrong direction.
C. Smooth muscle
Description: spindle-shaped cells with central nuclei; cells arranged closely to form sheets; no striations. (under
involuntary control)
Location: in the walls of hollow organs (ex. digestive tract, respiratory tract, uterus, blood vessels); in arrector pili
muscles of the skin (causes goose bumps)
Fxns: in hollow organs, smooth muscle propels substances along internal passageways (ex. food in digestive
tract, blood in blood vessels, the fetus in the uterus; eggs in fallopian tubes); heat is given off as a result of many
chemical reactions required for muscle contraction and the formation of a goose bump;
Slide: "Goblet Cell Epithelium (H215)" (l. p.) - look for smooth muscle tissue in the outer wall of the intestine; the
contractions of these muscle cells result in peristalsis (progressive, wavelike contractions that move food
through the digestive system). (Hint: you'll know it's smooth muscle - you'll be able to see the intestinal villi on
the slide!!)
IV. NERVOUS TISSUE
Initiates & transmits nerve impulses that coordinate body activities. Nervous tissue is composed of 2 major cell
types: neurons and neuroglial cells.
Description of neuron: nucleus-containing cell body (soma); cytoplasm is drawn out into extensions (sometimes
as long as 3 or more feet!); dendrites are the shorter branched extensions located close to the cell body dendrites conduct nerve impulses toward the cell
body - neurons may have many dendrites; axons are single, long extensions - axons conduct nerve impulses
away from the cell body - each neuron has only one axon.
Location: Brain, spinal cord, nerves
Fxns: neuroglial cells - special supporting cells that protect and insulate neurons, and 2.) neurons - cells
specialized to receive stimuli and to conduct nerve impulses to all parts of the body.
Slides:
1. "(H390) Motor nerve Cells, Smear, Ox Spinal Cord" (l. p.) - id. neuron soma & dendrites; also id. neuroglial
cells ("webby" substance with little purple dots); you won't be able to id. axons on this slide because the
axons have broken off; neurons on this slide are called multipolar because they have many dendrites
coming off the soma.
2. "Motor Nerve Endings, w.m." (l. p.) - id. axon; you can see the red skeletal muscle cells that the axon is going
to cause to contract!); observe the axon branches with “bulbs” on their ends.