What Is a Blastomere?
A blastomere is considered to be a cell with a nucleus inside containing genetic information. These cells are totipotent, that is, they are cells capable of generating a complete and functional individual.
The set of blastomeres is what forms the embryo and, finally, will be transformed into the blastula. For example, a good quality day 3 embryo should have between 7 and 9 embryonic cells or blastomeres.