Morula Cell

A morula is distinct from a blastocyst in that a morula (3–4 days after fertilization) is a mass of 16 totipotent cells in a spherical shape whereas a blastocyst (4–5 days after fertilization) has a cavity inside the zona pellucida along with an inner cell mass. A morula, if untouched and allowed to remain implanted, will eventually develop into a blastocyst.