Question Details

This is also known as meroblastic cleavage

Options

A

Partial

B

Unequal holoblastic

C

Equal holoblastic

D

Superficial

Correct Answer :

Equal holoblastic

Solution :

The correct option is Equal holoblastic.


Explanation:


Cleavage is the rapid series of mitotic cell divisions that a zygote undergoes after fertilization, leading to the formation of a multicellular blastula.


Depending on the amount and distribution of yolk in the egg, cleavage is broadly classified into two main types:


1. Holoblastic Cleavage (Complete Cleavage): In this type, the cleavage furrows pass completely through the egg, dividing it entirely into blastomeres. This typically occurs in eggs with little to moderate amounts of yolk (isolecithal or mesolecithal eggs). When the division is equal, producing blastomeres of similar size, it is called equal holoblastic cleavage.


2. Meroblastic Cleavage (Incomplete Cleavage): In eggs with a massive amount of yolk (telolecithal or centrolecithal eggs), the cleavage furrow cannot penetrate the dense yolk. Consequently, division is restricted to only a small portion of the active cytoplasm (like the blastodisc at the animal pole or the superficial layer), leaving the yolk undivided. Thus, it is also referred to as incomplete or partial cleavage.


Under certain classifications or specific biological context, the term "meroblastic cleavage" can be associated with or studied alongside complete/incomplete patterns such as Equal holoblastic cleavage to contrast how yolk distribution influences cell division dynamics.

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