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Microanatomy > Placental Development > Flashcards

Placental Development Flashcards

1
Q

End of 1st week

A

blastocyst superficially implanted

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2
Q

2nd week- Extraembryonic mesoderm created by hypoblast cells

A

Extraembryonic mesoderm is now chorionic plate)

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3
Q

13 Day

A

Trophoblastic lacunae present @ embryonic & abembryonic pole

Uteroplacental circulation begun

2nd yolk sac lined by endoderm

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4
Q

Villi

A

formed by syncytium

Rests on a layer of cytotrophoblastic cells that cover core of villi

Cap sys developing in core of villi soon comes in contact w/ capillaries of chorionic plate & connecting stalk

Gives rise to extraembryonic vascular sys

Beginning week 3

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5
Q

Week 9

A

Nutrient demand increase

Increase surface area b/t maternal & fetal placenta

intrervillous spaces are lined by syncytium

Cytotrophoblastic cells surround trophoblast & entirely in contact with endometrium

Suspended by connecting stalk

Cytotrophoblast shell completely surrounds chorionic sac

  • Protective & attaches chorionic sac tightly w/ decidual
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6
Q

Chorion Frondosum & laeve

A

Villi on embryonic pole continue to grow & expand- frondosum

Villi on abembryonic pole degen & by month 3= chorion laeve

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7
Q

Cytotrophoblast

A

In week 4, endovascular invasion by cytotrophoblst

Cytotrophoblast epithelial to endothelial transformation during month 4

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8
Q

Preeclampsia

A

maternal hyperT & proteinuria due to reduced organ perfusion

May progress to eclampsia w/ seizure

Reversible by baby delivery

Trophoblast disorder where cytotrophoblasts don’t diff and don’t undergo epith to endothelial transformation

Invasion of maternal BVs by these cells is rudimentary

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9
Q

Placenta components

A

Decidua basalis = maternal

Chorion frondosum = fetal

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10
Q

Amniotic fluid

A

Dispositon of fetal mem due to increased production of amniotic fluid

10 weeks= 30 mL; 20 wks= 450 mL; 37 wks= 1000 mL

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11
Q

End of 3rd month

A

amnion has expanded so that it comes in contact with chorion

Fusion of amnion & chorion to form the amniochorionic mem obliterating chorionic cavity

This mem ruptures during labor (breaking of H2O)

Yolk sac then usually shrinks & gradually obliterated

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12
Q

Umbilical Cord

A

week 5- primitive umbilical ring

week 10- primitive umbilical cord

2 arteries in blue & 1 vein in red (fetal reversed circulation)

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13
Q

Placenta in 2nd half of pregnancy

A

months 4 & 5- decidual septa project into intervillous space but do not reach chorionic plate

Decidual speta have core of maternal tissue & covered by syncytial layer, which separate maternal blood from fetal tissue of villi

Decidual septa divide placenta into cotyledons (compartments)

Placenta growth // to uterus. Covers up to 30% of internal surface of uterus

Increase in thickness of placenta due to arborization of villi.

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14
Q

Full term placenta

A

Torn from uterine wall at birth

Expelled from uterine cavity as afterbirth

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15
Q

Circulation of Placenta

A

maternal blood goes into intervillious space

80-100 spiral endometrial a. in pulsatile manner spurts maternal blood toward chorionic plate

As P dissipates, blood flows slowly over branch villi to allow gas exhange, nutrient & metabolic products

Blood returns through endometrial v. to maternal circulation

A red of circulation can result in fetal death

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16
Q

Placenta mem/barrier

A

Separates maternal & fetal blood

Endothelial lining

CT

cytotrophoblast

syncytium

@ month 4= thins into 2 layers (endothelial & syncytium)

Normally no mixing!

17
Q

Erythroblastosis & Fetal Hydrops

A

when some fetal blood cells escape across placental barrier, can elicit Y response by mom

If mom response is sufficient- Y will attack & hemolyze fetal blood cells= hemolytic diseas of the fetus & newborn (erythroblastosis fetalis)

In rare case= anemia so severe that fetal hydrops occurs where edema & effusions into body cavities–> lead to death of fetus!

18
Q

Severe Cases of Erythroblastosis & Fetal hydrops

A

by CDE Rhesus blood group sys & D or RH antigen is most dangerous

Maternal Y response occurs when fetus is D (Rh) + & mother is D (Rh) -

19
Q

Placenta f

A
  1. exchnage gas, nutrition & electrolytes
  • O2, CO2 & CO simple diffusion
  • short term interruption of O2 supply is fatal
  1. transmission of maternal Y
    * IgG transported from mother to fetus @ 14 wks. Fetus gains passive immunity
  2. Hormone production by syncytiotrophoblast
  • progesterone! By 4th month, placenta should produce enough to maintain preg & CL can degen
  • also makes estrogen, hCG & lactogen/somatomammotropin
20
Q

Synthetic esrogen diethylstilbestrol DES

A

cross placenta easily, can cause carcinoma of vagina & abnormalities of cervix & uterus in female

Also in male testes who were exposed to DES

21
Q

Many viruses

A

rubella, cytomgalovirus, Coxsackie, variola, varicella, measels, poliomyelitis virus

Cross placenta w/o difficulty

Some can cause infections, which results in cell death & birth defects

22
Q

Microorganisms

A

treponema, pallidum, syphilis & toxoplasma gondii

Damage brain & eyes

23
Q

Most Drugs

A

cross w/o difficulty so serious damage

Heroin & cocaine can cause fetal habituation

24
Q

Amniotic Fluid

A

Protective cushion

From 5th month fetus swallows it & fetal urine added dialy to amniotic fluid

polyhydramnios= excess >1500

oligo= decreased <400

25
Q

Umbilical Cord Abnormalities

A

Cord can encircle neck of fetus

If short can cause problems during delivery by pulling the placenta from its attachment site

26
Q

Amniotic bands

A

result from tears in amnion

bands may encircle part of fetus & constrict limb

amputations & craniofacial deformities

27
Q

Premature rupture of mem

A

PROM

rupture of mem before uterine contractions in 10% of pregnancies

28
Q

Twins

A

Dizygotic/fraternal tiwns= simultaneous shedding of 2 oocytes & fertiliz by diff spermatozoa

Ea zygote implants indiv & develops its own placenta, amnion & chorionic sac

monozygotic/identical tiwns= splitting of zygote. Occurs in early blastocyst stage. Common placenta, chorionic cavity but separate amniotic cavity. Strong resemblance in blood groups, fingerprints, sex

Triplets, quadruplets, quintuplets are rare

29
Q

Dizygotic Twins

A
30
Q

Monozygotic

A
31
Q

Abnormalities with twins

A

Perinatal mortality & morbidity & increase in preterm delivery

Vanishing twin (fetal resorption)- deaht of 1 fetus & its mummification

Twin-twin transfusion syndrome TTTS/ stuck twin

Microanatomy (9 decks)

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