Zoo-Lab (Sem-1) - Exercise 8: Histology

histology

the study of normal tissues

tissue

a group of cells which maybe associated by a common origin and by similarity of function or form

epithelial tissues

form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands; specialized to protect, absorb, and secrete

glands

epithelial structures produced by epithelial tissues that perform secretory functions

intercellular substance

cements the cells together; very small amount in epithelial tissues

basement membrane

a condensation of the connective tissue at the surface of its contact with the epithelium where the epithelia rests upon

squamous

flat

cuboidal

squarish

columnar

rectangular

simple epithelia

consist of a single layer of cells all of which are in contact with the basement membrane

stratified epithelia

consists of several layers of cells superimposed one upon the other and only the cells at the basal layer come in contact with the basement membrane and only those at the superficial layer have free surfaces

basal layer

simple squamous epithelium

flattened, polygonal in shape; nucleus is round/oval and located at the center; boundary maybe irregular or smooth; cytoplasm is barely visible but maybe seen in the vicinity of the nucleus where it appears to bulge; found on the parietal layer of the Bowman’s capsule in the kidney/ lining of blood vessels, heart, and lymphatic ducts (endothelium)/ lining of the peritoneal, pleural, and pericardial cavities as serous membranes (mesothelium)

simple cuboidal epithelium

squarish cells w/ centrally located nucleus; nuclei are spherical and large

simple columnar epithelium

cells are taller than they are wide; nucleus is characteristically close to the base of the cell; found on the mucous lining of the stomach and intestine

simple columnar ciliated epithelium

on the free surface of the epithelial cells are ultrastructures, like the cilia, that helped the tissue in moving materials over it

pseudostratified columnar ciliated epithelium

nucleus gives an impression of stratification/layering, but upon close examination, all of the cells are attached to the basement membrane; on the free surface of the cells are hair-projections called cilia

stratified squamous epithelium

found on the epidermis of the skin; thin outer layer (darkly stained) epidermis; thick inner layer (lightly stained) dermis;

stratified columnar epithelium

corpus spongiosum; cells at the surface are columnar in form

polyhedral cells

cells in the layer below the columnar cells until the basal layer

connective tissues

most diverse (bone, cartilage, and blood) supports, protects, and gives structure to other tissues and organs in the body

connective tissue proper

responsible for binding and connecting different organs of the body together; abundant intercellular substances; cellular elements are few and scattered called fibroblasts

collagenous (white) fibers

a type of connective tissue fiber; the most common; long, wavy, and unbranching; consist of bundles of fine fibrils called fibrillae, which lie parallel to each other and give the fiber its longitudinal striated appearance; resistant to a pulling force; each fiber is made of protein collagen

elastic (yellow) fibers

occur singly (do not consist of fibrils); thin, straight, branching, and anastomose freely; they appear darker than the individual white fibrils; each fibril is made up of protein elastin; they can be stretched and returned to its original length

reticular fibers

fine, wavy, branching, and form a network; hard to distinguish or see in the specimen; components are identical with the collagenous fibers

areolar/loose connective tissue

serves as a filling tissue; contain less amount of fibers but with greater amount of ground substance, and greater number of cells

fibroblasts

responsible for the synthesis of fibers and ground substances which form the extracellular matrix; found along bundles of collagenous fibers; oval/fusiform-shaped; only nucleus is visible

mast cells

round/oval nucleus; cytoplasm is filled up w/ several hundreds of granules; believed to secrete histamine and heparin

fat/adipose cells

big cells containing a little amount of cytoplasm that surrounds a relatively big space which contained the fat globule; nucleus is flattened and displaced to one side of the cell; may occur singly but more often found in groups

dense connective tissue

divided into dense irregular (fiber bundles are randomly oriented) and regular (fibers oriented parallel to each other) tissues

dense irregular connective tissue

dermis; pinkish bundles of fibrillar structures are the collagenous fibers; small, dark blue in color are the nuclei of fibroblasts

dense regular connective tissue

tendon; parallel arrangement of collagenous fibers; fibroblast nuclei are located between the bundles of collagenous fibers

specialized connective tissue

perform other functions than connecting and binding tissues and organs together

adipose tissue

human skin; resemble signet rings; abundant in the subcutaneous layer (hypodermis) beneath the dermis; nuclei are located at the basal side of the cells

supporting tissues

these tissues form the framework of the body, including cartilages and bones

cartilages

soft, pliable, translucent, and avascular; form skeletal framework; cover the ends of long bones, forming articular surfaces, and protect the nose, larynx, trachea, and bronchi

hyaline cartilage

matrix is predominated by glass-like ground substance called hyaline; scattered around the matrix are spaces called lacunae, and lodged between them are the chondrocytes; the connective tissue covering the cartilage is the perichondrium

elastic cartilage

similar to hyaline cartilage; lacunae are scattered in isogenous groups of two or four cells called cell family; difference with the hyaline cartilage is this one has elastic fibers permeating

bones

rigid, hard, and brittle; hardness is caused by the deposition of inorganic salts, primarily calcium phosphate; storage depot of minerals and site of red blood cell formation

osteocytes

bone cells

lamellae

well-defined layers within a bone

periosteal lamellae

outermost bony layer

Haversian canal system/osteon

structural unit of the bone tissue; concentric lamellae-rings; canaliculi-tiny tubules; Haversian canal-center; osteocytes (within lacunae)-cells

interstitial lamellae

bony substance between the Haversian canal systems/osteon

vascular/circulating tissue

blood is a specialized connective tissue that transports oxygen, nutrients, and hormones into the cells

plasma

fluid matrix

frog’s blood

with nucleus

erythrocytes

red blood cells

leucocytes

white blood cells

human blood (erythrocytes and leucocytes)

RBC - flat cells with bioconcave discs devoid of nuclei/carriers of oxygen and carbon dioxide in the blood; WBC - lack of color, true cells with nucleus, divided to 2 groups: non-granular/agranulocytes and granular/granulocytes

monocytes

a type of agranulocyte; much bigger than lymphocytes; nucleus is indented and kidney-shaped/horseshoe-shaped

lymphocytes

a type of agranulocyte; larger than erythrocytes; big nucleus which stains deep blue; mechanism of immunity

acidophils/eosinophils

spherical in shape; cytoplasm stains bright red with acid dyes; nucleus is two oval bodies connected via thin chromatin thread; detoxification role

basophiles and neutrophils

basophils - difficult to find in the human bloodm(0.5-1% of leucocytes), granules of cytoplasm will stain dark blue; nucleus is polymorphic; neutrophils - spherical cells with cytoplasm that is not strongly acidic nor basic in its reaction; cytoplasmic granules will stain light pink/lavender; nucleus is elongated; phagocytes (kill bacteria)

muscle tissues

composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts

myofibrils

contractile fibrillar components

location

movement from one place to another

motion

movement of various parts of the body with respect to one another

skeletal muscle tissues

striated, voluntary muscles; cylindrical and multinucleated; with a thin membrane (sarcolemma) and liquid cytoplasm (sarcoplasm)

cardiac muscle tissues

striated, involuntary muscles; separated by intercalated/intercalary disks

smooth muscle tissueun

unstriated, involuntary muscles

nervous tissues

found in the brain, spinal cord, and nerves

neuron/nerve cell

structural and functional unit of nervous tissue

nerve/nerve trunk

composed of one or more bundles or groups of nerve fibers bound together by a connective tissue

nerve fiber

fibers in the nerve