implantation

Question 1

what is polyspermy

Answer 1

multiple sperm fertilizing ovum

Question 2

how do you prevent polyspermy by wave of polarization

Answer 2

1. wave of depolarization which repels sperm electrically and/or leads to the shedding of Juno (proteins)

-sperm can no longer bind to egg
-also called fast block

Question 3

how do you prevent polyspermy by cortical reaction

Answer 3

2. rising Ca2+ causes cortical vesicles to fuse with the membrane, releasing their contents (exocytosis)

-pushes zona away from oocyte
-hardens zona which makes enzymes difficult to digest away
-enzymes cause shedding of sperm receptor: Juno
-also called slow block

Question 4

how does zinc help with polyspermy

Answer 4

-prevents binding of sperm to ZP proteins
-ovastacin help significantly reduce sperm binding too

Question 5

during the early stages of cell division of the zygote/morula, what happens to the size of the zygote/morula

Answer 5

-same size throughout
-cells dividing but no where to go

Question 6

how often do you expect to see polyspermy

Answer 6

10%

Question 7

can the blastocyst implant in the endometrial wall upon arrival

Answer 7

no, because ZP around it

Question 8

are there any molecular signals that aid the blastocyst in binding to the endometrium

Answer 8

Yes, sLE expressed by epithelial cells by endometrium helps with implantation but not required for implantation

Question 9

how can a developing embryo get the nourishment it needs from the mother

Answer 9

-blood, glucose, oxygen, cellular respiration
-has access to circulatory system

Question 10

what makes the outer layer of the blastocyst

Answer 10

-trophoblast cells make up outer layer of blastocyst
-inner cell mass: will become embryo

Question 11

how does the ZP get dissolved

Answer 11

by proteases secreted by uterus

Question 12

what is decidualization

Answer 12

P4 increases release of glycoproteins and increases blood flow to endometrium

Question 13

what do trophoblasts express a receptor for

Answer 13

sLE-1 called L-selectin which anchors the blastocyst on endometrium

Question 14

what is the layer of trophoblast cells in contact with the endometrium called

Answer 14

syncytial trophoblasts which are important to push through the endometrium

Question 15

what are the trophoblast cells toward the lumen of the uterus called

Answer 15

cytotrophoblasts

Question 16

what do syncytial trophoblasts secrete

Answer 16

1. TNF-alpha: priming immune cells
2. peptidases
3. metalloproteinases
4. hCG (does same thing as LH)

Question 17

what is the function of hCG

Answer 17

stimulates corpus luteum

Question 18

what kind of receptors do luteal cells have in abundance

Answer 18

LH

Question 19

what would activation of these receptors cause luteal cells to release

Answer 19

-P4 prevents mitosis, apoptosis, and secretion of sLE protein for endometrium
-increase of P4, endometrium in tact

Question 20

what is the presence of hCG indicative of

Answer 20

pregnancy

Question 21

when the cells of the endometrium start to grow around the blastocyst is called?

Answer 21

deciduoma response

Question 22

what is the function of cytotrophoblasts

Answer 22

differentiate into different trophoblast cells that remodel stroma and blood vessels

remodel spiral arteries to bathe embryo in blood

Question 23

spiral arteries

Answer 23

modified by trophoblast cells and natural killer cellsa

Question 24

are the circulatory system of embryo/fetus separate from the mother

Answer 24

yes, they are 2 closed systems

Question 25

what is the purpose of the placenta

Answer 25

-source of O2, glucose, nutrients for embryo/fetus enter via umbilical vein
-elimination of CO2, waste via umbilical artery