cleavage and implantation Flashcards
What is one of the roles of the zona pellucida?
It surrounds the early embryo and prevents it from adhering to anything along its journey to the uterus so that an eptopical abortion is avoided.
What would you predict would be the possible outcomes of the embryo hatching too early from the zona pellucida?
Sticking to the oviduct or even falling into the abdominal area will lead to pregnancies developing there. Eptopic pregnancies have many complications i.e. rupturing the intestine which causes intense pain.
When the oocyte has been fertilised by the sperm, what is the correct order of the development of the fertilised oocyte?
Zygote > Morula (@ 16 blastomeres) > blastocyst
What does cleavage refer to?
A series of mitotic divisions of the zygote.
What are the cells formed in cleavage called?
Blastomeres
What process do the blastomeres become tightly packed?
Compaction
How many blastomeres constitute a morula?
16 blastomeres.
What are the cells called in the inner morula?
The inner cell mass or the embryoblast.
What are the cells forming on the outside of the morula called?
The trophoblast.
What is cavitation?
When the trophoblast cells start secreting fluid into the centre of the morula and a cavity is formed.
Transformed from a solid ball of cells to a hollow ball of cells.
What is the decidua basalis?
Surrounds the embryo separating it from the rest of the uterus.
What does the decidua capsularis do?
Separates the embryo from the uterine cavity.
What does the decidua parietalis do>
It is the rest of the uterus.
What may be the cause of spontaneous abortions.
A mechanism which prevents the development of embryos with genetic abnormalities.
Genetic analysis of spontaneously aborted embryos shows that ~50% of them exhibit some type of chromosomal abnormality.
What are the consequences of tubal pregnancies?
It may cause the uterine tub to rupture.
