9.28 Fertilization

Question 1

the ability of cells to form the syncytiotrophoblast is due to an ancient viral protein called ________

Answer 1

syncytin

Question 2

Problems with ________ are a common cause of female infertility since they are needed to move the egg down the tube

Answer 2

cilia function

Question 3

_________ twins occur when there are two ovulations, two fertilizations, and two implantations

Answer 3

dizygotic

Question 4

what is the slow block for polyspermy?

Answer 4

Slow block - cortical reaction. space between egg membrane and zone pellucida - perivitelline space. Enzymes secreted here

Question 5

upon fusion of the sperm with the oocyte membrane, the second meiosis is ___________ and one set of maternal chromosomes is expelled into a second ___________.

Answer 5

completed

polar body

Question 6

what is the fast block to block polyspermy?

Answer 6

Fast block - change in membrane potential among initial binding that prevents further sperm fusion events

Question 7

the __________ is a part of the trophoblast with one nucleus per cell.

Answer 7

cytotrophoblast

Question 8

after fertilization, the zygote undergoes cell divisions, making a 8-16 still stage called the ______ stage, where cells are _______ with each other (not too strongly though)

Answer 8

morula

associated

Question 9

the ___________ digests through the uterine wall, surrounding the ___________ during invasion. Eventually, the ___________ will cover the whole embryo once buried in the uterine wall.

Answer 9

syncytiotrophoblast
cytotrophoblast
syncytiotrophoblast

Question 10

implantations of the zygote anywhere but the uterus. Usually in tube, but sometimes in body cavity

Answer 10

ectopic pregnancies

Question 11

A group of trophoblast cells close to the inner cell mass form the _____________ – multinuclear cells that lead to invasion of the uterine wall

Answer 11

syncytiotrophoblast

Question 12

If uterine tube becomes ______ or ______, it could prevent access of sperm to egg, or movement of the egg to the uterus.

Answer 12

scarred or inflamed

Question 13

what is the space called between the ovum membrane and zona pellucida during the cortical reaction?

Answer 13

perivitelline space

Question 14

attachment of _______________ cells to the uterine wall begins implantation. this is mediated by _______ on the cell surface of the invading cells.

Answer 14

syncytiotrophoblast

L-selectin

Question 15

glycoproteins surrounding the sperm head are removed in a process called _______

Answer 15

capacitation

Question 16

cells forming the outer layer of the blastocyst will form the _______

Answer 16

trophoblast

Question 17

the stage in which the cells form a sphere around a fluid filled space is called the:

Answer 17

blastula

Question 18

around __-__ days after fertilization, implantation occurs

Answer 18

5-6

Question 19

At around 100 cells, there is a division into the ________ and _______ cell mass. The inner cell mass becomes the _______ and the outer layers will make the _________ layer.

Answer 19

inner, outer cell mass
embryo
trophoblast

Question 20

the sperm must cross the __________ (granulosa cells attached to ovum) and __________ (inner glycoprotein layer) of the egg in order to contact the oocyte membrane. It does this through _________ enzymes released from the sperm tip.

Answer 20

corona radiata
zona pellucida
acrosomal

Question 21

___________ twins can be due to splitting to zygote during blastula stage.

Answer 21

monozygotic

Question 22

___________ twins can be due to formation of two separate inner cell masses

Answer 22

monozygotic

Question 23

The egg with a 1n nucleus and a polar body. Not fertilized, is called the _______.

Answer 23

ovum

Question 24

the making of the perivitelline space is called the _______________.

Answer 24

cortical reaction

Question 25

A fertilized egg. The fusion between the male and female pronucleus to form a diploid nucleus.
What is this structure not called?

Answer 25

zygote