Module 3 - Embryology and development pt1

Question 1

Label this image with:

uterine tube
ovary
oocyte
body of uterus
cervix
vagina
ampulla-site

Answer 1

Question 2

what is a secondary oocyte

Answer 2

The secondary oocyte has completed meiosis I but is arrested in metaphase II of meiosis II, awaiting fertilization to complete the second meiotic division

Question 3

what is ovulation

Answer 3

During ovulation, one ovary releases one gamete cell, called a secondary oocyte

Question 4

what is the germinal period

Answer 4

first 2 weeks of development; formation of primitive germ layers.

Question 5

what is the embryonic period

Answer 5

week 3 to end of 8th week; organ
systems develop

Question 6

what is the fetal period

Answer 6

9th week until birth; organ systems grow
and mature

Question 7

Differentiate clinical events and embryologists timeline

Answer 7

Question 8

Label with:
oocyte nucleus
zona pellucida
corona radiata
first polar body
sperm cell

Answer 8

Question 9

Explain how the sperm enters the oocyte

Answer 9

1. Sperm penetrates corona radiata
2. Sperm binds to ZP3 glycoproteins on the zona pellucida
3. Sperm binding causes an Acrosomal Reaction.
4. Zona pellucida is digested by the sperm.
5. Binding of integrin a6b1 on plasma membrane causes depolarization and that sperm enters the oocyte

Question 10

what stops multiple sperm from fertilizing the oocyte?

Answer 10

if the oocyte shrinks/zona pellucida denatures then the ZP3 receptor needed to digest the zona pellucida is inactivated (no acrosomal reaction)

Question 11

after the sperm enters the oocyte, how is fertilization completed?

Answer 11

The egg completes meiosis after the sperm enters.
Two pronuclei (male and female) form and fuse.
A diploid zygote (the fertilized egg) is created, ready for the next stages of development!

Question 12

how is a morula formed

Answer 12

zygote formed from fertilization divides over and over again until it reaches 12 cells around day 5 which is called the morula

Question 13

how is a blastocysts formed

Answer 13

during cleavage for the formation of the morula, the zygote stays the same size and its the cells that shrink meaning that the zona pellucida is still around the zygote.
during hatching, the morula breaks free from the zona pellucida and pushes the cells to form one layer with a cavity filled with fluid which is the blastocysts

Question 14

differentiate blastocele and trophoblast

Answer 14

blastocele is the cavity of the blastocyst and the trophoblast is the exterior that will eventually form the placenta and extraembryonic membranes.