Question

Oocyte activation encompasses a number of different processes and events that are critical for normal embryogenesis

a. what is meant by the 'activation' of the oocyte?

b. When and how (i.e mechanism) is it initiated?

c. What essential processes for normal development are initiated and which, if abnormal, can have deleterious downstream consequences for normal embryogenesis and why?

Answer 1

1. Oocyte activation is the process in which there would be conversion of the female gamete, referred to as the egg, into cells that would be supporting embryogenesis. This occurs by contact with sperm, as the sleek enters the egg and before fertilisation occurs.
2. The mechanism of initiation includes hardening of the egg’s outer layer, after entering of the sperm, which prevents additional spermicide from getting attached. This is referred to as the process of polyspermy block. There is mixing of the DNA from egg to the sperm. After combination of DNA, there has been the process of fertilisation that has taken place.
3. Normal process of embryogenesis occurs when there is proper cleavage, fertilisation , blastula formation, gastrula formation and somitogenesis. If meiosis does not occur properly or if there is no proper cleavage and morula formation, the embryo formation would be improper.