Placenta and Fetal Membranes Flashcards by Landon Riggs

Week 1, what do we have?

what gives rise to the embryo?

what gives rise to the placenta?

1 cell layer and inner cell mass

inner cell mass

trophoblast

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in week 1, what do trophoblasts give rise to cellularly?

Cytotrophoblast

Syncytiotrophoblast

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What is the job of Cytotrophoblasts?

syncytiotrophoblasts?

mitotically active stem cell layer that give rise to cells of the placenta –> also gives rise to the syncytiotrophoblasts

secrete enzymes that you can erode into the endometrial lining and it is going to release hCG for initial signal of pregnancy

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what day do we get implantation?

day 6

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Week 2, what is our embryo?

what comes from the epiblast?

bilaminar disc –> epiblast and hypoblast

primordial germ cells, also the amnion forms to make the amniotic cavity that will be filled with fluid.

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Decidua Reaction?

as the syncytiotrophoblast erodes into the endometrial lining, we get this.

it’s changing the endometrium, breaking up the endometrium decidua cells and when you lyse that you now have glycogen and nutrients to help nourish the embryo and helps provide immunologically privileged site so mom doesn’t reject foreign tissue.

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What does the hypoblast give rise to in week 2?

what are the different layers of it?

extraembryonic mesoderm –>

somatic extraembryonic mesoderm –> lines trophoblast and amnion

extraembryonic splanchnic mesoderm –> lining yolk sac

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What is derived from extraembryonic mesoderm?

what is coming from each?

Connecting stalk –> coming from somatic mesoderm –> becomes umbilical cord

Chorion –> coming from extraembryonic somatic mesoderm, cytotrophoblast, syncytiotrophoblast

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what is the chorion?

layer of placenta

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Hydatidiform mole?

what is it caused by?

what are you going to see?

abnormal growth of the trophoblast

abnormal proliferation of the syncytiotrophoblast and cytotrophoblast and remember syncytio is making hCG so you’ll have a ton of hCG.

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2 types of hydatididiform moles?

in both cases, what’s going to keep on growing?

clinical presentation?

what can happen because of this mole?

1) complete mole –> empty oocyte.. so fertilization of an empty oocyte followed by duplication of sperm. so cloning of one sperm

Partial –> fertilization of an empty oocyte by 2 sperm

2) Partial mole –> 2 sperm fertilize a normal egg.. zona reaction did not occur for polyspermy to be prevented.

vaginal bleeding, pelvic pressure or pain, enlarged uterus, morning sickness

Choriocarcinoma

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hydatidiform mole.. DNA test what would you get?

100% paternal because oocyte is empty

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Placenta has 2 parts, what is it?

what are each coming from?

fetal part and maternal part

fetal part from Amnion and Chorionic Sac

maternal part from the Decidua basalis and Decidua Capsularis

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Amnion is coming from what?

when is it formed?

where did it come from?

ectoderm

2nd week

epiblast

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Amniotic fluid?

what is it composed of? what are the particulates?

functions?

specific need for development?

composed of ions, glycophospholipids, steroids, particulates (cells of the embryo)

cushion against injury, maintains temperature, ease of movement, diagnostic information.

lung development and GI development.

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Amniotic fluid 3 sources of amniotic fluid?

Cells of the amnion

maternal blood

fetal urine

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Amniotic fluid once its formed happens to do what with the fetus?

fetal swallowing..

this primes the GI system –> goes into fetal blood –>

1) carried by umbilical arteries to the placenta and the waste will be exchanged
2) carried to fetal urine –> and that contributes to more amniotic fluid.

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Oligohydramnios?

3 causes?

too little amniotic fluid

renal agenesis (can’t produce amniotic fluid)

Placenta insufficiency (can’t make as much maternal blood and less amniotic fluid

premature rupture of the amnion.

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Polyhydramnios?

3 causes

too much fluid

anencephaly –> lacking most of your brain. brain isn’t fully developed, you don’t have the cranial nerves to help you swallow so you have way too much amniotic fluid.

esophageal atresia –> too much backup

hypo plastic lungs –> lungs can’t breathe in and out, you have a back up

Amniotic band syndrome?

2 things that could happen?

amnion are sloughed off and produce bands, wrapping around extremities.. face, head, digits, and cause amputations

exogenous –> external trauma

endogenous –> vascular supply isn’t good, become necrotic and slough off and cause constrictions

Chorion gives rise to what?

what’s in it?

villi

contain the blood supply to exchange gases and nutrients.

Chorionic Villi?

primary and secondary

start days 13/14 (week 2)

we get a fingerlike projection of cytotrophoblast.. the syncytiotrophoblast is eroding into the lining –> as it erodes we get pools of blood which are –> trophoblastic lacuna filled with maternal blood (there are also intervillous spaces forming)

secondary from 15-18

extraembryonic mesoderm forms finger like core of the villi. we still have the cytotrophoblast but it’s formed the cytotrophoblastic shell which is the interface between mom and the embryo. the syncytiotrophoblast is still eroding and the intervillous spaces are much larger

Chorionic Tertiary Chorionic villi?

Where are the branching villi going?

anchoring/stem?

days 19-21

extraembryonic mesoderm differentiated to villous capillaries.. so we have capillaries in these villous structures.

so now we have a tertiary chorionic villus with branching

all the branches are out in the intervillous spaces surrounded in mom’s blood so we can get the exchange of nutrients. anchoring villi and

anchoring / stem –> anchoring to the cytotrophoblastic shell towards the interface of mom

By week 8, what is the embryo covered in?

chorionic villi

What is the Decidua?

endometrium of the uterus. Decidua Basalis --> deep to the conceptus (what the egg invaginates into) Decidua Capsularis --> superficial part of the decidua overlying the conceptus (covering the ovary) Decidua Parietalis --> remaining part of the decidua (rest of the uterus)

The conceptus should not embed into what? what should it embed into?

myometrium.. just the endometrium

what happens to the villus chorion that surrounds the embryo? what does this fusion create? what happens to the different decidua as the embryo gets bigger? what degenerates?

as the embryo progresses, that embryo smushes on the chorion and it fuses.. so it becomes smooth chorion amnion and chorion fuse to form the amniochorionic membrane as the embryo gets bigger, next we get the decidua capsular and it fuses with the decidua parietals. as it becomes compressed, the lack of blood supply causes the capsularis to degenerate

when the embryo has gotten so big that it destroys the decidua capsularis, what happens to the smooth chorion?

fuses with the decidua parietalis and it's at that point that we no longer have uterine cavity.

Early placental layers and gas exchange?

early week 20 gas and nutrients are going through syncytio, cytotrophoblasts, CT, an then through the endothelium of the capillaries

Late placental layers and gas exchange? something's different!

cytotrophoblasts degenerate in the placenta. the vasculature are now closer to the proximity too (vasculosyncytial placental membrane) syncytio --> basement membrane --> basement membrane of capillary --> endothelial cells to get to blood of fetus

unless trauma.. what's to note about mom and baby blood?

mom's blood and baby's blood do not mix.

what do you accumulate in the late placenta surrounding the syncytiotrophoblasts? what do these structures show?

syncytial knots --> clusters of syncytiotrophoblasts that you have a late placenta

looking at a villus and you see 2 cell layers.. what stage are you in? single layer?

early villus. mid term villus (cyto are mostly gone)

Hofbauer cells?

placenta macrophages found in the inside of the branching villi.

How do you know its the maternal side of the placenta?

Cotyledon --> one or two main stem villi and all their terminal branching. they look separated because of the placental septum.

How do you know its the fetal side?

umbilical cord. and also covered in amnion so it'll look shiny.

how to tell fetal side vs maternal side on a histo slide?

decidua cells are purplish and you can see speckles throughout.. the amnion DO NOT have decidua cells

Placenta accreta? Placenta increta? placenta percreta?

placenta attaches to the myometrium placenta penetrates into the myometrium goes through the uterus and attaches to the serosa or adjacent organs

what happens if you have accreta, intreat, percreta during childbirth?

massive hemorrhage

Placenta Previa? 3 types? what do you NOT do?

3 types: 1) Marginal --> where the placenta is attaching too close to the internal Os 2) partial where the placenta is partially covering the uterine os 3) complete --> covering the entire uterine Os DO NOT DO A DIGITAL VAGINAL EXAM

hormones that cannot cross?

Hormones antibodies other than IgG heparin drugs bacteria except syphilis, toxoplasma gondii, listeria

Hemolytic Disease of the newborn

RH- mom and RH+ father, baby is RH+ that first baby is fine, but at delivery some of RBCs from baby can make it and be expose to mom. RH+ causes an immune reaction so mom produces ANTI RH Igs. second baby.. if it's also RH+, mom has antibodies so IgG can attack and cause anemia

Allantois?

it become the template for the umbilical arteries and umbilical vein.. it does not become it, but it provides the template!

What is the umbilical cord covered in? core of what? what vasculature? what was the template? what duct structure? any empty space?

amnion core of extraembryonic mesoderm 2 umbilical arteries and one umbilical vein allantois (for the template) vitello-intestinal duct extraembryonic coelom

true umbilical cord knot? absence of umbilical A?

prevent blood to and from the placenta so can kill the fetus usually associated with chromosomal abnormalities and mostly associated with cardiovascular defects

Dizygotic twins? monozygotic conjoined twins?

2 eggs ovulated at same time, each fertilized and both implanted identical twins --> depends on when the structure split. 1) if the 2 cell stage splits we get a trophoblast on one and trophoblast on the other so 2 placenta and 2 chorion and 2 amnion. 2) inner cell mass splits at week 1. so you have one chorion and one placenta, but 2 amnion forming. 3) split at week 2 --> one amnion, one chorion, one placenta. conjoined twins --> formed when the primitive streak has formed

can you tell mono from dizygotic apart?

yeah, if boy and girl.. dizygotic