Answer:
Explanation:
Blastula is an early stage of embryo development, it is the continuation of t morula which is when the zygote is moved to uterus.
Cells in blastula are actively dividing as formation is still taken place, and are used because this dividing cells are very large and can be easily seen. The chromosomes of Blastula are also more visible than human chromosomes hence necessitates it uses.
