Check of fertilization and embryonic development
On the day after the oocyte retrieval, it is checked microscopically if eggs have been fertilized or not. The successful implantation is indicated by the presence of two pre-cores, one of maternal and one of paternal origin in the ovum. The fertilized eggs are returned to the incubator in a different culture medium and patients are informed.
DAYS 2 & 3
The next step of embryonic development is its division into cells called blastomeres. Embryos are evaluated daily for the number, size, shape of blastomeres, and the existence or not of fragments. The second and third day after the egg collection they usually consist of 4 and 8 blastomeres respectively. The embryos are usually transferred on the second or third day.
DAYS 4 & 5
There are cases where the cultivation of embryos is extended until the fifth day after the egg retrieval. The fifth day, after several splits, the embryo has taken the form of the blastocyst.