Histology Lecture 4: Characteristics of Epithelial Tissues I Flashcards
What is the material that lies outside of cells and plays a support role in holding the cells together
matrix
resemble epithelial tissues but lack exposure to a lumen
epithelioid tissue
surfaces of the cell that are in contact with the lumen
apical domain
include the surfaces of cells that are locked together by
special junctional complexes with neighboring cells as well as the surface opposite the apical domain that is in contact with the basal lamina
basolateral domain
two parts of the basement membrane
basal lamina and reticular lamina
next to the epithelial layer and is 50-80 nm
thick. It is composed of type IV collagen plus glycoproteins and is PAS+. It is absent in lymph vessels and hepatic sinusoids as these structures are designed to be leaky.
Basal Lamina
is in contact with underlying connective tissue and consists of argyrophilic (“silver loving”) fibers, reticular fibers and glycoproteins
Reticular Lamina
Functions of the Basement Membrane
1) Selective filtration barrier; 2) Scaffold for embyrogenesis and regeneration; 3) Stabilization of tissue shapes
This epithelium appears to be stratified, but all cells are in contact with the basal lamina, so it is technically a simple epithelium. The appearance of stratification is due to the variable positions of the nuclei within the cells
pseudostratified epithelium
This is thought to be a type of simple epithelium but with the appearance of having more than one layer because of the positions of the nuclei. All cells are in contact with the basal lamina, but the dome-shaped surface cells give the appearance of stratified epithelium. This category of epithelium is associated with the urinary track and may
be referred to as urothelium
Transitional Epithelium
Characterized by surface modifications such as cilia or microvilli and face a lumen or external environment
apical domains
The sides and bases of the cells are characterized by intercellular junctions. These cell surfaces are in contact with the basement membrane and surrounding cells/
Basolateral domains
a microtubular structure that forms the basic structure of the cilium
axoneme
contains nine triplet microtubules in a helicoid array without a central microtubular component
basal body
consists of an axoneme formed by a central pair of microtubules surrounded by nine concentrically arranged microtubular pairs. This assembly is known as the 9 + 2 microtubular doublet arrangement
cilium
finger-like cell projections of the apical epithelial cell surface containing a core of crosslinked microfilaments (a
polymer of G-actin monomers).
microvilli
formed by microvilli and typically indicate an absorptive function of the cells
brush border
long and branching finger-like projections of the apical epithelial cell surface that contain a core of cross-linked actin but NO AXONEME.
stereocilia
Lines lumina of ducts, vessels, and other tubular structures as well as forms walls of alveoli, Bowman’s capsules and inner surfaces of membranous labyrinth and tympanic membrane
simple squamous epithelia
In side view, cells may be low or high (approaching almost squamous or almost columnar). May have a brush border (kidney tubules) on apical surface composed
of microvilli. Found on surface of ovary, pigmented epithelium of retina, kidney tubules, glands and ducts, terminal bronchioles, choroid plexus, and anterior capsule of lens of eye.
simple cuboidal epithelium
May have a striated border (intestinal cells) on apical surface composed of microvilli. Ciliated version is found in the upper respiratory tract, uterine tubes, uterus, paranasal sinuses, and the central canal of the spinal cord. Non-ciliated version is found in the digestive tract beginning with the cardia of the stomach, the gall bladder, and in parts of the excretory ducts of glands, and is often associated with Goblet Cells.
Simple columnar epithelium
Heavily keratinized version is found in the epidermis with connective tissue papillae and in the cornea without connective tissue papillae. Lightly or non- keratinized version is found in the esophagus, vagina, lining of the mouth, tongue, and part of the epiglottis.
stratified squamous epithelium
Seldom found, but may occur in small areas of the anal mucosa, large excretory ducts of some glands, and part of the male urethra
Stratified cuboidal epithelium
Seldom found; occurs in the ducts of adult sweat glands, fornix of the conjunctiva of the eye, parts of the male reproductive/urinary tract, the pharynx, and the epiglottis
Stratified columnar epithelium
ciliated version found in the trachea. Version with stereocilia is found in the epididymis.
pseudostratified epithelium
similar to microvilli but are longer and often branched; long, branched, non motile cilia
stereocilia
functions primarily in secretion of enzymes and mucous and absorption of nutrients and fluids
simple columnar epithelium
indicative of highly keratinized epithelium
absent nuclei in the outermost layer
indicative of transitional/urothelium
dome-shaped cells
Simple, non ciliated columnar epithelium is most likely to be found associated with what tissue
digestive tract
Junctional complexes are associated with which cellular domains?
Basolateral
Transitional epithelium is associated with which systems?
Urinary system
stratified cuboidal epithelium may be found where
part of male urethra
Lightly keratinized stratified squamous epithelium is characteristic of what tissue
vaginal epithelium
