EVERYDAY SCIENCE

Detailed explanation-1: -blastula, hollow sphere of cells, or blastomeres, produced during the development of an embryo by repeated cleavage of a fertilized egg. The cells of the blastula form an epithelial (covering) layer, called the blastoderm, enclosing a fluid-filled cavity, the blastocoel .

Detailed explanation-2: -A blastocyst is a hollow ball of cells. The cells form two layers. The inner layer is about three to four cells thick and the outer layer is about one cell thick. The cells in a blastocyst divide rapidly.

Detailed explanation-3: -The blastula is a hollow ball of cells organized into an epithelial monolayer. Midway through the blastula stage, the embryo secretes hatching enzyme, which results in proteolytic degradation of the fertilization envelope.

Detailed explanation-4: -Each cell within the blastula is called a blastomere. Cleavage can take place in two ways: holoblastic (total) cleavage or meroblastic (partial) cleavage.

Detailed explanation-5: -A morula is a microscopic ball or cluster of cells formed through cell division very early in the embryonic development that occurs after the formation of a zygote through fertilization (the uniting of the sperm and egg) but before the blastocyst stage.