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34 Cards in this Set

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trophoblasts in human blastocyst
develop into placenta
inner cell mass in human blastocyst
give rise to fetus
monozygotic twins
20% dichorionic diamnionic
80% monochorionic diamnioic
1% monochorionic monoamnionic
lateralization of blastocyst
continues to day 5
at time of hatching inner cell mass is split with each group of cells expressing different genes
individuals produced have same DNA, but differential gene expression
Implantation
5-7 days post ovulation - the blastocyst begins to interact with the endometirial surface epithelium
- once the trophectodermal trophoblasts have firmly become attached to the endometrial surface, trophoblasts begin to invade through the epithelial layer an dinto the enometrial stroma
day 21
organs formed
How does the fetus get oxygen?
from the mother's blood that circulates in the placenta
30-35% partial pressure of PO2
cord accidents abruption (seperation of the placenta)
How much blood does a uterus have?
.5% no pregnancy
20-25% during pregnancy
Role of fetal fibronectin
glue
also surrounds fetus
Normal spiral arteries
in the non pregnant state, the uterine spiral arteries are very small
only .5% of a non-pregnant women's cardia output enters the uterus
Increased blood flow happens how?
invasive trophoblasts enlarge the mother's vessels to increase blood flow to the uterus
4-5 weeks after trophoblasts invade leave placenta causing expansion of uterus that brings mor o2 --- if not, pregnancy fails
Invasive trophoblasts
vessel wall destroyed increasing blood flow
how do we assess pathology in a placenta?
look at placenta
abnormalities
umbilical cord goes to edge rather than middle
vessels in membrane
what can go wrong in pregnancy?
immunologic attack
maternal lymphocytes can attack the placenta
t-cells can attack chorionic villus
CD3 immunohistochemistry - mother rejecting placenta
dichrorionic diamniotic fused
decreased maternal blood flow to placenta
spinal arteries and invasice trophoblasts
failure to convert maternal spiral arteries
Pregnancy will fail if
trophoblasts fail to expand vessels - also leads to gestational HTN
gestational HTN
placenta does not get enough blood b/c the vessels are not big enough
uterus need to be removed
small blood flow leads to
a small fetus
decreased flow causes
fibrin to collect around the villi - fibrin clots can lead to calcification and possibily death of placental tissue
the trapped villi eventually die
what can go wrong with pregnancy?
immunologic attach
decreased maternal blood flow to placenta
infection
ascending infection
most common route for an intrauterine infection - bacteria from vagina
fighting an infection
WBCs
neutrophils first attach the bacteria fromt he external membrane
the mother's neutrophils also attach the bacteria throught he chorionic plate
eventually even the fetus will begin to attack the bacteria with its neutrophils
How do infections harm the fetus?
damage caused by inflammatory cytokines
bacteria within the amnitic fluid induces an inflammatory response which causes cytokine release
the cytokines can damage the placenta the baby
there is biolgical variability in the cytokine network
when the fetus is stressed
the villi form syncytial knots
syncytial knots are the source of..
corticotropin releasing hormone
CRH is criticial for
fetal cortisol
production and organ maturation
CRH made by
syncytial knots entering the fetal circulation
CRH causes the fetus to produce
cortisol (steriods)
Cortisol presares the fetus for
delivery, including promoting lung maturation
Cortisol also increases
placental CRH production (positive feedback)
Stressed fetus in uterus
will deficate
the bowel contents will eventually dissolve in amniotic fluid
the meconium material slowly dissolves into the membranes that surround the fetus
after several days, little meconium is visible in the amniotic fluid, but the pigmented meconium can be seen in the membrances using a microscope
when the fetus is stressed it will make
nucleated RBCs
when o@ levels drop
the marrow increases RBC production and nucleated RBCs are released
Nucleated RBCs can be best seen in
the umbilical cord vessels