Stage of 16 cells is
A morula is distinct from a blastocyst in that a morula (3-4 days post feilization) is a 16-cell mass in a spherical shape whereas a blastocyst (4-5 days post feilization) has a cavity inside the zona pellucida along with an inner cell mass
Embryo
Morula
Zygote
Blastocyst
General anatomy