Week 1

After the zygote is formed, it starts dividing mitotically, a process called Cleavage. And each cell thus formed is called Blastomere. Till 8-cell stage, these blastomeres are discrete following which they undergo Compaction.

 3^rd day- 16-cell stage called Morula (mulberry shaped) is formed. Morula consists of two cell groups-

·         Outer cell mass- which later form trophoblast.

·         Inner cell mass- which later form the embryo proper.

4^th day-

1.       Blastocyst formation takes place

·         Outer cell mass forming trophoblast

·         Inner cell mass forming embryoblast (attached to one pole)

·         Cavity called blastocele

2.       Zona Pellucida disappears