tissue part 2 Flashcards
This refers to the structural modifications along the lateral, apical and basal surfaces of the epithelium
surface specializations
Lateral surface specializations includes
glycocalyx, junctional complexes, lateral interdigitations and gap junctions.
Basal surface specializations includes
basal lamina/basement membrane, caveolae and hemidesmosomes
Apical surface specializations includes
microvilli and cilia.
the most common junctional complexes.
macula adherens
These are little bodies that are distributed in a spotty way around individual cells.
Macula adherens or Desmosomes
macula means
spot
Under the TEM, macula adherens is composed of
several dark and light parallel lines representing the layers a cell membrane of adjacent cells.
It anchors cells to each other; gives the epithelium coherence and strength
macula adherens
cytoplasmic folds on the lateral surfaces of adjacent cells that interdigitate with each other.
lateral interdigitations
not for adhesion but for communication between adjacent cells. They are 20 angstrom in size and the site for lowered resistance to passage of ions.
gap junctions
the non-living amorphous substance produced by epithelial cells.
basement membrane
the basement membrane is made up of
proteoglycans particularly sulfate, laminin, fibronectin, and type 4 collagen
why is the basement membrane not identifiable under light mirsocope in HE sections
because it is thin
Under the TEM, basement membrane is consists of an
electron dense basal lamina made up of fine filament
a bulb-like invaginations of the basal cell membrane that may contain mitochondrion and associated with active transport of finished products at slower rate.
basal folds or caveola
is a half desmosome facing the basement membrane.
hemidesmosome
long, finger-like cytoplasmic projections from the apical or luminal border of epithelial cells, giving the epithelium a striated or brush border.
microvilli
They are much smaller (10 μm long and 1 μm thick) than cilia (10-100 μm long and at least 10 μm thick) and lack microtubules.
microvilli
hair-like processes projecting from the apical border of the epithelial cell.
cilia
2 types of cilia
kinocilia and stereocilia
a motile cilia that helps in the movement of materials along a sheet of epithelium.
kinocilia
They increase the surface are of the epithelium for absorption.
kinocilia
structurally similar to microvilli except that the stereocilia are long and branched. It is restricted to the lining of the epididymis and vas deferens and the receptor hair cells of the auditory and vestibular system in the inner ear.
stereocilia
they are nonmotile structure which increase epithelial surface area and facilitate movement into and out of cells
stereocilia
a type of epithelium that covers the outer surfaces of the body and organs; lines the lumen of tubular organs.
surface epithelium
an epithelial sheet containing one layer
simple
are thin, flat cells with centrally located round to oval, basally located nucleus. cells have fried egg shape and irregular outlines
squamous cell
cells that are approximately as tall as they are wide and with round to oval, centrally located nucleus.
cuboidal cells
distinctly taller that they are wide with oval nucleus located basally.
columnar cells
composed of one layer of extremely thin, flat cells with an almost visible cytoplasm and a clearly visible round to oval nucleus bulging prominently.
simple squamous epithelium
Highly suited to line structures with filtering/transporting function, like the parietal layers of the glomerular capsule, blood vessels (endothelium) and body cavities (mesothelium), where a “slick‘ surface facilitates flow of fluids.
simple squamous epithelium
Because of its delicate structure, the epithelium cannot withstand “wear and tear”.
simple squamous epithelium
composed of one layer of cuboidal (square) cells. This form of epithelium function as secretory absorptive cells and is found in several types of renal tubule, endocrine glands (thyroid follicles) and exocrine glands.
simple cuboidal epithelium
cells also comprise the nonsecretory/nonabsorptive linings of tubules like
ducts of glands, the retinal pigment epithelium,the surface of the ovary as germinal epithelium, on the surface of the lens and in small bile ducts
undergoes constant functionally dependent development and regression.
simple vuboidal epithelium on luminal surface
consists of cells that are distinctly taller than they are wide. The nuclei are predominantly oval (their long axis being aligned with the apical–basal cell axis) and may occupy a basal, central or apical position
simple columnar cells
typically associated with absorption or secretion.
simple columnar cells
one layer of typical columnar cells lining the medium-sized ducts of exocrine glands
simple columanar with typical columnar cells
[One layer of fan-shaped mucus-secreting columnar cells with wide vacuolated apex and narrow base containing oval nucleus
SCE with mucus secreting columnar cells
has vacuolated apical cytoplasm in H&E section due to dissolution of mucin secretion by alcohol during tissue dehydration
SCE with mucus secreting columnar cells
Fan-shape because the apical regions of adjacent cells expand uniformly with the accumulation of mucin granules exerting equal pressure against each other. Lines the glandular portion of the stomach],
SCE with mucus secreting columnar cells
[One layer of secretory (goblet) and absorptive (typical columnar) cells; goblet cells like a wine goblet with an expanded theca (apical region) that contains mucin granules and a narrow stem (basal region) that contains a dense granules, interspersed between typical columnar cells;
SCE with secretory and absorptive cells
Lines the small and large intestines
SCE with secretory and absorptive cells
[One layer of secretory and ciliated columnar cells; Secretory columnar cell presents apical bleb (bead-like cytoplasmic projection) in the apical border;
ciliated columnar cells
presents Kinocilia (hair-like projections) in the apical border and lines the fallopian tube].
ciliated columnar cells
a special form of single-layered surface epithelium in which all cells are in contact with the basal lamina, yet not all reach the free surface.
pseudostratified epithelium
The cell nuclei lie at different levels, such that the cells appear to be arranged in two or more ‘rows’. This creates the false impression that the epithelium is multi-layered (stratified).
psuedostratified
widespread in the respiratory tract (respiratory epithelium) where the apical cell surface features numerous cilia.
pseudostratified
the epididymal tract is lined by
pseudostratifies bearing stereocilia
The primary role of stratified epithelium is
protection
Types of stratified epithelia are based according to
shaped of cells in the superficial layer, irrespective of the shape of underlying cells.
composed of two or more layers of cells consisting of basal layer, middle layer and superficial layer. Basal layer is composed of cuboidal to columnar cells that rest on a wavy or undulating basement membrane, irrespective of the shape of underlying cells. Middle layer/s with one to several layers of polyhedral or polygonal cells. The superficial layer/s is composed of one to several layers of squamous cells that lie parallel to the luminal or external surface.
stratified squamous epithelium
2 types of stratified squamous epithelium
keratinzed or cornified and nonkeratinized or non-cornified.
dead anucleated squamous cells filled with keratin granules).
keratinw
an epithelial adaptation to wear and tear on abraded surfaces.
keratinization
normally occurs only in stratified squamous epithelium not in other stratified types
keratinization
This type of StraSquaE can be found in the foot pads, hoof, bovine muzzle, buccal cavity, anal region and ruminant forestomach.
keratinized
is composed of two or more layers of cells. In two cell layers, the basal layer is composed of cuboidal cells and superficial layer is composed of columnar cells. For three or more layers, the basal layer is composed of cuboidal cells, the middle layer with polygonal cells and superficial layer of cuboidal cells.
stracolumnar
This type of epithelium lines large excretory ducts of the exocrine glands (e.g. parotid salivary gland)
stracolumnar
refers to the changing shape of superficial cells of the epithelium, depending on the state of contraction or distension of the organ lined.
transitional
is a specialized form of stratified epithelium. Its
transitional
composed of two or more layers of cells. In two cell layers, the basal layer and superficial layer is composed of cuboidal cells. For three or more layers , the basal layer is composed of cuboidal cells, the middle layer with polygonal cells and superficial layer of cuboidal cells.
stracuboidal
This type of epithelium lines large excretory ducts of the exocrine glands (e.g. parotid salivary gland).
stracuboidal
Its deepest (basal) layer consists of cuboidal to columnar cells that are connected to the basal lamina. These cells are overlaid by irregular ‘mushroom-shaped’ cells that become rounder towards the surface, forming caps over the deeper cell layers
transitional
found in the excretory passages of the urinary system (renal pelvis, ureter, bladder, and urethra) where great mechanical changes may occur due to contraction and distension
transitional
As these structures are subjected to constant changes in pressure and distension, the epithelium can undergo rapid changes in height. These cells are water impermeable due to large numbers of zonula occludens between cells.
transitional
protects the urinary tract from damage caused by the presence of hypertonic urine (in mammals and birds), and also prevents dilution of the urine by osmosis
water impermeability of transitional
in transitional, In contracted/collapsed or relaxed state, the cells in the basal layer have
basal layer- columnar
the middle layer of 2-4 cells- polyhedral or polygonal in shape
superficial layer with 2-3 layers- balloon-shaped/mushroom-shaped cells with convex free surfaces.
transitional In distended or stretched condition,
basal cells appear cuboidal in shape.
Middle layer has polyhedral cells
superficial layer is composed of 1-2 layers of squamous cells.
the site for lowered resistance to passage of ions
gap junctions
9 doublets of microtubules arranged in circularly around a central pair of microtubules
axoneme
the simple cuboidal epi is found jn
renal tube, endocrine glands, exocrine glands
it lines the glandular portion of the stomach
simple cuboidal with mucous secreting
why is the simple columnar mucous secreting fan shaped
bec of adjacent cells expanding uniformly with accumulation of mucin granules
