Answer:
Cleavage, morula, blastocyst, gastrula
Explanation:
The zygote is formed after fertilization of sperm and ovum. Then the zygote undergoes a repeated cell division to form a number of cells. These tiny cells formed by mitotic cell division but present inside the zygote. It forms 2 cells then 2 cells, then 8 cells and so on. After forming the number of cells the zygote has a number of tiny cells. This stage is called morula and the tiny cells are called morulae. Then these cells migrate towards the periphery of the morula and creating a central space called blastocoel. This hollow ball structure is known as the blastocyst. After this blastocyst stage, the cells migrate to form 3 layers such as endoderm, mesoderm, ectoderm. From this layer different organs are formed. This 3 layered stage is known as gastrula. Thus the zygote development starts from cleavage, morula, blastula, and gastrula.
