Pre-Implant Embryo Development And Genetic Diagnosis Flashcards
What occurs in the cleavage (first) stage of pre-implantation?
The embryo continues to divide every 12-24 hours up till the 8-16 cell stages. The cells, or blastomeres, are distinct but in contact.
What is a morula?
An embryo in the compaction stage of pre-implantation after further cell division.
In the compaction (second) stage of pre-implantation, what are the inner and outer regions of the morula called?
Inner cell mass, trophectoderm
What the outer trophectoderm cells of the morula form?
Trophoblast and the chorion, the embryonic part of the placenta.
What are two factors that have been proposed in determined in cell fate in the morula?
Position at the morula stage, angle of cell division
What is zona hatching?
The blastocyst must first hatch from the zona prior to implantation into the uterine epithelium.
Outline the procedure for pre-implantation genetic diagnosis (PGD).
Removal of one or two cells from embryos that the 4 to 8 cell stage by mechanically puncturing the zona and then using micromanipulation equipment under a microscope.
Name three ethical issues that PGD raises.
Sex selection, designer babies, and saviour siblings.
Where does fertilisation occur?
The ampulla of the oviduct.
