does a zygote form into a blastocyst yahoo answers
A fertilized egg is a zygote for about 3 days. Then it becomes a morula; a couple of days later, it is a blastocyst. After about 2 weeks (from conception), it is an embryo.At 10 weeks, it is a fetus. Source(s): http://health.allrefer.com/health/fetal-...http://www.religioustolerance.org/abo_fe...t is then when the mass of cells divide into the three derms, or layers, of cells: the endoderm (inner), the mesoderm (middle), and the ectoderm (outer). When the three derms have distinctly formed. The embryo does not become a fetus until after the end of the embryonic period some six weeks later.