12. Week 1 - Beginning of Development Flashcards
What is the Day 1 product of fertilization?
Zygote
What is the Day 2 product of fertilization?
2-cell Blastula
What is the Day 3 product of fertilization?
4-cell Blastula
What is the Day 4 product of fertilization?
Morula
What is the Day 5 product of fertilization?
Blastocyst
Where does fertilization occur?
In the ampulla of the uterine tube.
What is cleavage?
A series of MITOTIC divisions of the zygote. Total cytoplasmic volumes remians constant.
Describe the morula.
At the 32-cell stage, the blatomeres form a morula consisting of an inner cell mass and an outer cell mass.
Describe the blastocyst.
Blastocyst formation occurs when fluid secreted withing the morula forms the blastocyst cavity: The inner cell mass is know as the embryoblast and the outer cell mass becomes the trophoblast.
What does the trophoblast convert to?
It turns into the cytotrophoblast and syncytiotrophoblast which both become part of the placenta.
What must happen to the zona pellucida in order for implantation to occur?
It must degenerate.
Where does the blastocyst most frequently implant?
In the posterior wall of the uterus. The embryonic pole of blastocyst implants first.
At what phase of the mesntrual cycle does the blastocyst implant?
During the progestationla phase.
