Histology review Histology What to look for Histology Practical = 50 pts Some slides set up on scopes (~10) Some Powerpoint pictures on the projector Questions I will ask: What kind of tissue? General function? (e.g. absorption, protection) What 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) Muscles (3 types) or neruons Integument and accessory structures Epithelial tissue Simple cuboidal epithelium Another example - kidney Lining kidney tubule Large, spherical, usually central nucleus 1
Simple squamous Simple squamous Really flat cell layer. Cytoplasm very thin, visible only at point of central nucleus Kidney Superficial view (squamous) Simple columnar Simple columnar Intestinal lining Oblong nuclei which may be much closer to one side than the other 2
Pseudostratified Columnar Epithelium Trachea Look like multiple layers ciliated Another example Figure 4 5b Transitional Epithelium Urinary bladder Looks stratified, with no coherent layers and dome shaped cells at the top Transitional Figure 4 4c Stratified Squamous Epithelium Stratified squamous Skin Many layers thick, flat cells at top Figure 4 3b 3
Stratified squamous Stratified Cuboidal Epithelium Sweat gland ducts Two layers with large spherical nuclei Figure 4 4b Stratified Columnar Epithelium Salivary gland duct Only top layer lining lumen looks columnar Connective tissue Figure 4 5c Connective tissues Areolar tissue 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 A loose CTP 4
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 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: what to look for Reticular fibers (network) Found? Internal framework in many sort organs (liver, spleen) supporting the parenchyma 5
Dense regular Dense regular: what to look for Thick parallel bundles of collagen Thick fibers Little space in between fibers Small fibroblast nuclei in between bundles Found? Tendons, ligaments, deep fascia. Dense irregular More dense irregular Dense irregular: what to look for Elastic tissue Mesh of collagen fibers (irregular looking) Interspersed fibroblasts Found? Dermis of skin, periosteum, perichondrium 6
Elastic tissue Elastic tissue: what to look for Elastic fibers (instead of collagen fibers) in large bundles Smaller width fibers More space in between fibers Fibroblast nuclei (sometimes visible) Found? Between vertebrae, in blood vessel walls (underneath endothelium) Fluid CT Blood: what to look for Blood 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 7
More hyaline Hyaline cartilage 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) 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 cartilage 8
Elastic cart: what to look for Fibrocartilage Many elastic fibers in matrix (or sometimes to the sides) Chondrocytes in lacunae, often stacked up like a totem pole Found? External ear Fibrocartilage: what to look for Supportive CT: Bone Irregular, wispy collagen fibers Chondrocytes in lacuna Found? Intervertabral discs of spine, pads in knee joint Bone: what to look for Nervous Tissue Osteon (whole circular structure) Concentric lamellae (of matrix) Central canal (at center of lamellae) Osteoblasts Osteocytes in lacunae Canaliculi Found? Bones! Figure 4.10 9
Nervous Tissue Nervous tissue: what to look for Large, pyramidal cell bodies Long processes extending out Space (it s a smear so cells don t usually take up the whole area) Found? Nerves, CNS Figure 4.10 3 Types of Muscle Tissue Muscle Tissue: Skeletal Skeletal muscle: large body muscles responsible for movement Cardiac muscle: found only in the heart Smooth muscle: found in walls of hollow, contracting organs (blood vessels; urinary bladder; respiratory, digestive and reproductive tracts) Figure 4.11a Muscle Tissue: Skeletal Skeletal Muscle: what to look for Long, cylindrical cells with obvious striations (stripes) Multinucleate cells with the nuclei at the periphery (not in the center) Figure 4.11a 10
Muscle Tissue: Cardiac Cardiac Muscle Figure 4.11b Cardiac Muscle: what to look for Muscle Tissue: Smooth Branching, striated cells interlocking at intercalated discs Uninucleate cells Figure 4.11c Muscle Tissue: Smooth Muscle Tissue: Smooth Sheets of spindle-shaped cells with no striations Central nuclei Figure 4.11c 11
Epidermis and dermis Integument Epidermis Dermis: Papillary vs. Reticular layer 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 What to look for: Again Papillary layer has ridges is areolar Just under basal lamina Reticular layer much thicker Dense irregular CT 12
Merocrine sweat gland Apocrine 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 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 13
Sebaceous glands Sebaceous follicle What to look for: Associated with hair follicle Found most everywhere hair follicles are found in skin Look like cauliflower (maybe?) 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 Random Examples Can you figure them out? 14
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