Lecture B9 Flashcards
The placenta is the site of exchange for _____ and
contains tissues from _____
-nutrients, wastes, O2, and CO2 between the mother and the fetus
-both individuals
The major functions of the placenta are performed by _____
-trophoblast cells
Trophoblast cells are derived from the _____ of the early ____ and are the first ____ formed
-trophectoderm
-blastocyte
-extraembryonic lineage
problems with pregnancy, miscarriages, preeclampsia = _____
problems with trophoblasts
placenta forms ___ to increase SA of placenta
villi
Primary villi of placenta appear _____ after implantation as _____ covered by _____ extend into______ containing maternal blood.
-2 days
-simple cords of proliferating cytotrophoblast cells
-syncytiotrophoblast
-lacunae
Secondary villi begin to form on about the ____ of embryonic development as the primary villi are ______
-15th day
-invaded by extraembryonic mesenchyme
Tertiary villi develop within a _____ as mesenchyme in the secondary villi differentiates to form _____
-few more days
-capillary loops continuous with the embryonic circulatory system
By the end of the first month of the pregnancy, the placenta contains _____, each branching many times and each branch having _____
-thousands of tertiary chorionic villi
-one or more capillary loops
Exchange of gases, nutrients, and wastes occurs between fetal blood in the capillaries and maternal blood by bathing ______
-the villi, with diffusion occurring across the trophoblast layer and the capillary endothelium
To begin implantation, receptors on cells of the _______ bind glycoprotein ligands on the ______.
-outer embryonic trophoblast
-endometrial epithelium
The trophoblast forms an invasive, outer syncytial layer called the ______
-syncytiotrophoblast
The trophoblast differentiates during implantation into: ______
-cytotrophoblast (CT)
-syncytiotrophoblast (SCT)
cytotrophoblast (CT) descr.
-layer of undifferentiated mitotically active cells immediately around the amnion and yolk sac
CT cells synthesize _____ to prevent _____
-anti-inflammatory cytokines
-an adverse uterine reaction to the implanted embryo
Syncytiotrophoblast (SCT) descr.
-outer layer, nonmitotic mass of multinucleated cytoplasm that invades the surrounding stroma
-formed by fusion of CT cells
-In direct contact with maternal blood and mediate exchange of nutrients and gases
SCT cells produce ______
-hormones/factors needed for pregnancy maintenance
By about the ninth day after ovulation, the embryo is implanted in the endometrium
and derives _____. The endometrial stroma undergoes ______ in the period following implantation. _______ become enlarged, polygonal, more active in protein synthesis,
and are now called ______ .The whole endometrium is now called the ____
-nutrients primarily from blood there
-histologic changes
-Fibroblasts
-decidual cells
-decidua
ST is facing the ____ and turnover when?
-maternal blood
-throughout pregnancy
CT able to self renew or differentiate by _____
-fusing to form ST layer
vili tree formation is important for _____
exchnage of nutrients, wastes and gas
CT are always ____
actively fusing
ST is marked by expression of _____
chronic gonadotropin beta (tested in pregnancy)
CT is marked by expression of _____
e-cadherin (had tight junctions; lateral membrane)
blastocyst implantation into endometrium is dependent on _____
-trophoectoderm (with microvilli) & endometrium integrins
-pinopodes
-early EGF signalling
-prostagladin & LIF production
SCT descr.
-highly polarized, extensive microvilli, syncytial, endocrine, major site of gases/nutrient exchange
trophoblast subtypes
-Synctiotrophoblast (SCT),
-Villous cytotrophoblast (VCT) -progenitor cell
-Cytotrophoblast cell column (CCC)
-Extravillous trophoblast (EVT) populations (endovascular and interstitial EVT)- anchor placent in uterus
_____ induce microvilli formation in trophoblast cells
-Flow shear forces (needs to not too high/low)
Human trophobalst stem cells have the capacity to give rise to the _____
-three major trophoblast lineages
Human trophoblast stem cells and primary trophoblast cells have similar ______
-transcriptomes) patterns of gene expression) and methylomes (epigenetic marks)
trophoblats are marked by ___
EGF+, Wnt+, TGFB-
Urine is transported by the _____ from the ______where it is stored until emptying by micturition via the ______.
-ureters
-renal pelvis to the urinary bladder
-urethra
The walls of the ureters are similar to that of the _____, with mucosal, muscular, and adventitial layers and becoming gradually _____ closer to the bladder. The mucosa of these organs is lined by the _____
-calyces and renal pelvis
-thicker
-uniquely stratified uroepithelium or transitional epithelium
Cells of this uroepithelium are organized as three layers: ______
- single layer of small basal cells on thin basement membrane
-intermediate region contains one or more layers of cuboidal or low columnar cells; terminally differentiates when umbrella cells are lost
-superficial layer of large bulbous or elliptical umbrella cells,
highly differentiated to protect the underlying cells against the potentially cytotoxic effects of hypertonic urine
functions of bladder epithelium (urothelium)
-storing urine for extended periods
-maintains the urine composition similar to that delivered by the kidneys.
to complete functions, urothelium _______
- minimum epithelial surface area-to-urine volume; this reduces SA for passive movement of substances between lumen and blood
-the passive permeability of the apical membrane and tight junctions is very low to electrolytes and nonelectrolytes.
-the urothelium has a hormonally regulated sodium absorptive system; thus passive movement of sodium from
blood to urine is countered by active sodium reabsorption (specific channels)
Uroepithelium expansion and contraction in response to bladder filling and emptying method
a) Umbrella cells in relaxed unfilled state
b) The bladder filling stimulates exocytosis of the vesicles (made of 2 apposing plaques- make asymmetrical unit membrane) coupled with endocytosis
c) The exocytosis of the vesicles leads to increased in the size of umbrella cell apical membrane
d) Upon voiding the added apical membrane is internalized and a new pool of vesicles are made in the Golgi
Umbrella cells are key to this barrier as well as _____ layer, unique composition of lipids and proteins in apical layer. Umbrella cells alter their apical surface by _____
-high resistance tight junctions, apical glycosminoglycan
-exocytosis and endocytosis
uroepithelia: About 70–90% of apical membrane is occupied
by ______. Remaining 10–30% is hinge area and is a _____
-0.5-μm-diameter protein-containing plaques
-normal lipid bilayer membrane
The thick muscularis of the ureters does what?
moves urine toward the bladder by peristaltic contractions and produces prominent mucosal folds when the lumen is empty.
Umbrella cells are up to 100 μm in diameter, have
extensive _____. Most of the apical surface consists of _____ (twice as thick as the inner leaflet) These regions are composed of ______ of stiffened plaques 16 nm in diameter.
-intercellular junctional complexes surrounding
unique apical membranes.
-asymmetric unit membranes
-lipid rafts containing mostly integral membrane proteins called uroplakins that assemble into paracrystalline arrays
The abundant membranous plaques, together with the _____, allow this epithelium to serve as an _____ protecting its cells and the cells of surrounding tissues from hypertonic urine and preventing dilution of the stored urine.
-tight junctions
-osmotic barrier
The turnover rate of uroepithelial cells is much _____ as compared to intestinal epithelial cells of ____
-slower at ~ 3 to 6 months
-3 to 5 days
SC of uroepithlia is not yet identified but likely _____
rside in basal layer (niche) because they have B1 intergrin and retain DNA labels for a long time (marker for SC)
cornea function
-protect eyes from germs, dust etc. with eyelipids, tears, and sclera (white of eye)
-acts as outermost lens
-controls and focuses light entry into eye
-most of eye’s focusing power
cornea descr.
-transparent
-avascular
-mechanical strenght from 200 collagen lamellae (criss-cross the cornea)
-thick
-richest sensory nerve supply
cornea have 5 distinct layers:
-external corneal epithelium, which is a stratified squamous epithelium
-anterior limiting membrane (Bowman membrane), which is the basement membrane beneath the corneal epithelium
-thick stroma;
-posterior limiting membrane (Descemet’s membrane), which is the basement membrane of the endothelium
-inner simple squamous endothelium.
cornea: Epithelium
-outermost region
- about 10 percent of the tissue’s thickness
-primary function: block the passage of foreign material, such as dust, water, and bacteria, into the eye and other layers of the cornea
-provide a smooth surface that absorbs oxygen and cell nutrients from tears, then distributes these nutrients to the rest of the cornea
-filled with thousands of tiny nerve endings that make the cornea extremely sensitive to pain when rubbed or scratched.
cornea: bowman’s layer
-directly below the basement membrane of the epithelium
-a transparent sheet of tissue
-composed of strong layers of collagen fibers.
cornea: stroma
-comprises about 90 percent of the cornea’s thickness
-water (78 percent) and collagen (16 percent)
-avascular
-collagen gives the cornea its strength, elasticity, and form
-shape, arrangement, and spacing of collagen are essential in producing the cornea’s light-conducting transparency
cornea: descemet’s mebrane
-a thin strong sheet of tissue that serves as a protective barrier against infection and injuries
-composed of collagen fibers (different from those of the stroma) made by the endothelial cells below it
-highly regenerative after injury
cornea: endothelium
-extremely thin, innermost layer of the cornea
-endothelial cells are essential in keeping the cornea clear. -Normally, fluid leaks slowly from inside the eye into stroma so it pump this excess fluid out of the stroma.
taken together, all the layers of cornea, these regions are responsible for
the overall stiffness, strength, extensibility, and toughness of the cornea
The corneal epithelium is ____, ______ layers thick, and comprises about 10% of the corneal thickness. ____ have a high proliferative capacity important for renewal and repair of the corneal surface and emerge from stem cells in
the ______.The flattened surface cells have _____
protruding into a protective tear film of lipid, glycoprotein, and water.
-nonkeratinized
- five or six cell
-The basal cells
-corneoscleral limbus encircling the cornea
-microvilli
the limbus region descr.
-encircles the cornea
- transitional area where the transparent cornea merges with opaque sclera
-Border between corneal and conjunctival epithelium.
-contains the corneal epithelial stem cells (limbus stem cells)
Corneal epithelium is a _____ tissue and sc reside preferentially in _______
-self-renewing
-basal layer of peripheral cornea in the limbus zone, rather than uniformly in the entire corneal epithelium
SC of cornea are marked by ___
CD43-, K3-, K14+
cornea CELLS are marked by ___
CD43+, K3+, K14-
The ratio of _____ determines switch from stem cell to corneal differentiations.
-SP1 to AP2
TF activation of cornea
AP1 activates K14
SP1 activates K3
SP1/AP2 transcription factors have over lapping binding sites on target genes
