Developmental sequence of an embryo from an Egg (oocyte) to an Expanded Blastocyst:
Day 0
Mature Eggs (oocytes)
Day 1
Fertilized Eggs
Day 2
4-cell Embryos
Day 3
8-cell Embryos
Day 4
Morula 10-30 cells Early Blastocyst
Day 5
Expanded Blastocyst
Day 6
Hatching Blastocyst