Answer
Differences between morula and blastocyst
The morula is a ball of cells that derives from cleavage divisions of the zygote. At about 3-4 days after fertilization, this ball of cells ( still within the zona pellucida) consists of about 32 rounded cells . The cells are similar and the ball is solid.
At about Day 5 ( after fertilization) changes take place in the morula that cause a cavity to develop within the ball of cells . The cells flatten somewhat as uterine milk seeps into the ball and forms the blastocyst cavity. In this way an outer trophoblastic layer and an inner cell layerare differentiated.
Work Step by Step
The 32 spheroid cells of the morula ball are very similar. During blastocyst formation fluid seeps in between the cells and flattens them creating a central fluid-filled blastocyst cavity. The wall of the blastocyst has two kinds of cells. The outer cells will form the trophoblast, and the inner cells will form the embryo. The chorion and the fetal portion of the placenta derives from the trophoblast. The inner blastocyst cells will form the inner cell mass which will give rise to the organs of the embryo.
