ANATOMY

Detailed explanation-1: -The zygote is entirely divided into the daughter cells or blastomeres. The two categories of cleavage depend on the amount of yolk present in the egg and those are holoblastic, where total or entire cleavage takes place and the second one is meroblastic cleavage also known as partial cleavage.

Detailed explanation-2: -Meroblastic cleavage takes place in those eggs where the amount of yolk is high, which leads to the partial or incomplete cleavage. It is basically of two types spherical and discoidal. The discoidal type of cleavage takes place in the reptiles and birds whose eggs are telolecithal in nature.

Detailed explanation-3: -In the absence of a large concentration of yolk, four major cleavage types can be observed: radial holoblastic, spiral holoblastic, bilateral holoblastic, and rotational holoblastic cleavage.

Detailed explanation-4: -as birds has megalecicithal eggs, the yolk provides resistance to cleavage, hence the cleavage is meroblastic & discoidal.

Detailed explanation-5: -Determinate. Indeterminate. Holoblastic. Meroblastic.