Implantation & 1st Trimester

Question 1

Compactation

Answer 1

Tight junctions formed between blastomere

Formation of morula

Question 2

Hatching, Apposition & Adhesion

Answer 2

ICM contributes to chorion & placenta

Blastocyst enters uterine lumen 5 days after fertilization

Apposition= ICM aligns // to endometrium

Question 3

Invasion

Answer 3

trophectoderm diff into cytotrophoblasts (inner cells on fetal side) & syncytiotrophoblasts (outer cells on maternal side)

Question 4

EVT extravillous trophoblast

Answer 4

invasive trophoblasts

hypoxia inducible factor HIF- drives EVT formation

• HIF stimulated by hypoxic environment

Forms cytotrophoblastic shell over decidua

Aggressively infiltrate decidua

EVT remodels spiral a.!

Secretes VEGF like synctiotrophoblast (also hCG B) while EVT secrete hCG hyperglycosylated

Question 5

Summary

Answer 5

cytotrophoblasts give rise to synctio & EVTs

STs form cell mass that will fomr placenta proper & secrete tons of hCG

CTs diff into EVTs due to low O2

EVTs highly invasive & secrete VEGF so invasion & remodeling of spiral a is successful

O2 T is low= 1st trimester, aggressive trophoblast invasion

O2 T is high= 2nd trimester through parturition, no invasion

Question 6

Decidualization- Blastocyst

Answer 6

Question 7

Junctional Zone

Answer 7

inner 1/3 of myometrium adj to basalis layer of endometrium

Highy packed w/ m. cells

Increased vascularity

Question 8

Secretory phase in uterus

Answer 8

trophoblasts invade JZ

deep placentation

needed for normal placental f

Question 9

Inadequate Remodeling of Spiral A.

Answer 9

trophoblastic remodeling did not extend into JZ

Decreased blood flow

Associated w/ preeclampsia >140/90

Restricts O2 & nutrient flow to developing fetus

Question 10

Miscarriage

Answer 10

Spontaneous before 20th week

Preterm delivery after 20th

Most occur before 7th week

Recurrent early pregnancy loss- 3 or more consecutive pregnancies lost before 20th week of gestation

Live birth only 30% of pregnancies

Question 11

Luteal Phase Defect

Answer 11

LPD

recurrent preg loss or infertility

Where endometriu fails to undergo proper diff or differentiates slowly.

Blastocyst invades but doesn’t implant adquaetly & abordted

Question 12

Integrin fibronectin sys

Answer 12

integrin surface spanning binding proteins that adhere fibronectin

Fibronectin is glycoprotein

Integrins expressed in endometrium luminal epith

Drives apposition & adhesion

Question 13

Vasoactive cmpds

Answer 13

VEGF, PGF & endothelins

Interact w/ proteins to form new vessels

For spiral a. angiogenesis

Question 14

MMPs

Answer 14

MMP-9 implantation

GF & other enz stimulate production of MMP-9 during invasion

Acts on spiral a. & decidua to ease placentation

Inhibited by TIMPs

Question 15

Prolactin

Answer 15

Marker for decidualization

Produced by stromal cells decidualized

acts on PRL R

secretory phase

Question 16

Fetus-Maternal Exchange

Answer 16

Through syncytiotrophoblast

Question 17

HCG

Answer 17

Question 18

hCG

Answer 18

Total HCG- pregnancy test

B Hcg- doubles every 48-72 hrs during early pregnancy (if not high enough levels ectopic/inadeq implantation/spontaneous abortion)

HCG-H- secreted by EVTs, highest during early preg, if elevated past 20 wk= down’s

nicked hCG & hCG free B- ?

Question 19

hCG-H

Answer 19

Low or undetectable by 20 wk in normal

Question 20

hCG endocrine

Answer 20

1. hCG rescue of CL

• binds to LH R of granulosa-lutein cells to maintain luteal progesterone
• bind to LH on theca-lutein to maintain luteal androgen output & contribute to progesterone

2. suppress GnRH release

• reduce FSH & LH from pit
• inhibit recrutiment of more follicles
• CL responds to hCG

Question 21

hCG paracrine

Answer 21

1. stimulate EVTs
2. maintain endometrial cell quiescence
3. increase sacculation of endometrial glands
4. increase glandular secretions
5. after invasion stim further hypertrophy of spiral a.

Question 22

hCG binding to LH R

Answer 22

Question 23

Luteal Placental Shift of Pregnancy

Answer 23

Steroid production shifts from CL to placenta

7-9 weeks of gestation

If remove ovary before 6- abortion more likely

after 10th- no problem

Estriol production begins @ 8 week of gestation

Need to have progesterone to maintain pregnancy

Question 24

Steroidogenesis in Maternal-Placental-Fetal

Answer 24

Question 25

Hormone Change

Answer 25

Progesterone- for differentiation of endometrium in early secretory & myometrial contractility to inhibit expulsion.

Estrogens vasodilators so enough blood around embryo. Also uptake of LDL cholesterol

Luteal placental shift= estriol appears & hCG declines

Question 26

Estrogens

Answer 26

Estrone is 5 times less potent than estradiol

Estradiol is 20 to 100 times greater than estriol

*stim breast dev also*