histo- block I Flashcards
(15 cards)
how to identify simple squamous epithelium?
single layer of flattened cells with a bulging oval shaped nucleus
- adjacent cells fit closely together to form a continuous sheet
- on surface view, they look like a mosaic
what are the 4 types of simple epithelium?
- simple squamous epithelium
- simple cuboidal epithelium
- simple columnar epithelium
- pseudostratified epithelium
where are simple squamous epithelium found?
common in the body
- lining of the alveoli
- walls of blood vessels
how to identify simple cuboidal epithelium?
single layer of cells where length & width of cells are the same
- have a spherical, round nucleus
through surface view, they are arranged in a polygonal/hexagonal type pattern
where are simple cuboidal epithelial cells found in the body?
- salivary glands
- thyroid follicles
- tubules of kidneys
how to identify simple columnar epithelium?
length of cell is more than the width - look like columns
- nucleus is oval/elongated & located near base of cell
- nucleuses in a sheet of columnar cells are located at around the same level
from a surface view, they looks the same as simple cuboidal but the outline of cells is much smaller
where is simple cuboidal epithelium found?
widely distributed in the body
- lining of stomach, intestines, gallbladder, uterus
how to identify pseudostratified epithelium?
False appearance of multiple layers w/ ciliated top
- all cells rest on the basement membrane (touch the bottom) but not all reach the top
- nuclei are at diff levels (this gives the false appearance of many layers)
where is pseudo stratified epithelium found in the body?
lines conducting part of respiratory tract (nose, trachea, bronchi, nasopharynx)
lines major male genital ducts (duct of epididymis and ductus deferens)
stratified squamous keratinized vs. stratified squamous non-keratinized epithelium (identification)
both: deepest layer (on basement membrane) has cuboidal/columnar cells that divide mitoticallly to send cells up
- as cells go up, they become more polyhedral in shape and at the most top layer, completely squamous (become increasingly flattened as you go up)
stratified squamous keratinized: outermost layer lacks nuclei (b/c its just a layer of dead cells)
stratified squamous non-keratinized: outermost layer has nuclei present
where are stratified squamous keratinized & stratified squamous non-keratinized found?
lines those surfaces which are subject to wear & tear
stratified squamous keratinized: areas that are dry after wear & tear
- ex. skin epidermis
stratified squamous non-keratinized: areas that stay wet after wear & tear
- lining of oral cavity, oropharynx, esophagus, cornea
how to identify stratified cuboidal epithelium? where are they found in body?
2-3 layers of cuboidal cells
in body: restricted distribution, but mainly lining of salivary & sweat glands
dont have mitotically dividing basal layer, not continuously replaced cells
how to identify stratified columnar epithelium? where is it located in the body?
columnar surface cells that rest on a layer of cuboidal cells
in body: restricted distribution, lining of conjuctiva of eyes, parts of male urethra, soft palate, epiglottis
dont have mitotically dividing basal layer, not continuously replaced cells
transitional epithelium cells (contracted vs. relaxed state)
special type of stratified epithelium that lines the lower urinary tract
- present in bladder, kidney, urethra
- can accommodate to stretching (needed when bladder gets full)
- deepest layer is of cuboidal cells
- then cells become pear shaped in the middle
- and finally near the surface look like domes (called umbrella cells- some even contain 2 nuclei)
relaxed: looks like 6+ layers
contracted: only about 2-3 layers, umbrella cells also become flattened at the top and look kind of squamous
