MCDB 240: Placenta

Question 1

what does the corpus luteum make?

Answer 1

progesterone

Question 2

progesterone leads to what kind of event?

Answer 2

endometrial differentiation

Question 3

what happens to progesterone levels if there is no pregnancy? if there is?

Answer 3

they decrease; progesterone inactivates certain proteases that lead to menstruation; progesterone prevents sloughing

Question 4

what does the blastocyst create to maintain pregnancy?

Answer 4

human chorionic gonadotropin (LH copy) to stimulate corpus luteum to produce progesterone (specifically from synctiotrophoblasts)

Question 5

describe human chorionic gonadotrpin

Answer 5

nCG mRNA and proteins are first things made by embryo

• pregnancy tests for hCG
• leads to morning sickness; more of this indicator of healthy pregnancy

Question 6

describe how plan B aborts pregnancy?

Answer 6

help to induce a lot of progesterone for interference?

Question 7

describe in basic terms how the embryo is like a parasite

Answer 7

placenta takes over mother’s pituitary gland by making its own hormones

• after 8 weeks, placenta makes its own progesterone
• remove ovaries, pregnancy would still continue

Question 8

describe the three layers to the placenta

Answer 8

• trophoblast: no HLA genes, so undetected by immune system
• cytotrophoblasts (originate from trophoblasts)
• syncytiotrophoblasts: produce hormones, like progesterone

Question 9

what is the top cause of abortion?

Answer 9

immune system rejection

Question 10

what role does the father play in trophoblast invasion?

Answer 10

the father’s gene patterns dictate trophoblast behavior, fitting in with the evolutionary hypothesis of male roles; up the bloodflow to the uterus (parasite reference)

Question 11

describe how the placenta is supported by mother’s uterus

Answer 11

endometrial milk feeds roots of placenta; irregular endometrium doesn’t make enough nutrients

Question 12

describe the parts fo the placenta

Answer 12

decidua (actually part of endometrial lining in mother) - prevents placenta from invading uterus (or else it would kill mother), slouged off every month b/c every month, woman preps for trophoblast invasion

Question 13

describe the villus

Answer 13

layer of synctriotrophoblast surrounding cytotrophoblasts, which surround fetal capillaries (blood/nutrient exchange)

Question 14

describe the first trimester

Answer 14

syncytiotrophoblast produces a lot of hCG, and cytotrophoblasts = stem cells, don’t produce any hCG

Question 15

describe the third trimester

Answer 15

decrease in cytos, sync’s begin making a lot of hPL’s, which turn off ability for mother to store nutrients

Question 16

describe anchroing trophoblasts

Answer 16

attach to the endometrium, w/ the help of fetal fibronectin, which glues placenta to mother and keeps bacteria out

Question 17

describe spiral arteries and what role do trophoblasts play

Answer 17

• very small in non-preg state; trophoblasts increase bloodflow to uterus
• failure to convert maternal spiral arteries leads to decreased perfusion

Question 18

in what cases do the mother, or the embryo dies?

Answer 18

• if uterus is ruptured, mother dies (too much blood loss to survive)
• if trophoblasts are faulty, too little bloodflow for embryo to survive

Question 19

what is the role of oxytocin?

Answer 19

uterus contracts to prevent blood leakage when placenta is removed after pregnancy

Question 20

describe the brain v. placenta relationship

Answer 20

• cytotrophoblasts differentiate into syncytiotrophoblasts, w/ fuses w/ overlying interstitia
• how to bend surfaces? Have 2 layers of cells; one proliferates faster, bilayer bends
• autism = genetic disorder, w/ abnormal folding of placenta may correlated w/ abnormal folding in brain