Question

Which of the following cleavage patterns takes place in human?

A Bilateral holoblastic cleavage
B Rotational holoblastic cleavage
C Centrolecithal meroblastic cleavage
D Bilateral meroblastic cleavage

Answer 1

The cleavage pattern in humans is B Rotational holoblastic cleavage, where the egg undergoes complete division and forms a multicellular blastula, characterized by the blastocyst in mammals.

Step-by-step explanation:

The cleavage pattern that takes place in humans is B Rotational holoblastic cleavage. In humans, a placental mammal, the eggs contain a very small amount of yolk and therefore undergo holoblastic cleavage, which is complete division of the egg. This differs from meroblastic cleavage, which occurs in species like birds with eggs that have a lot of yolk and is a partial division. During human embryonic development, after fertilization, the zygote begins a series of rapid mitotic cell divisions, known as cleavage, to form a multicellular structure. Following cleavage, the resulting embryo, at over 100 cells, is referred to as a blastula, characterized in mammals by the blastocyst stage. Additionally, humans, as deuterostomes, undergo indeterminate cleavage where cells at the early embryonic stage have the potential to become any cell type and are capable of forming identical twins if separated.

Answer 2

The cleavage pattern that takes place in humans is Bilateral holoblastic cleavage. Thus option A is correct.

Step-by-step explanation:

Bilateral holoblastic cleavage occurs in humans during early embryonic development. This type of cleavage involves complete division of the egg into smaller cells, and it occurs in a bilateral or symmetrical manner along the embryo. Holoblastic cleavage signifies that the entire egg is involved in the division process, resulting in the formation of blastomeres, which further develop into a blastula. In humans, this cleavage pattern is crucial for the initial stages of embryonic development, establishing the basic body plan and setting the stage for subsequent differentiation and organ formation.

Bilateral holoblastic cleavage can be explained as a process where the zygote undergoes divisions that are both complete and symmetrical. Each division results in the formation of blastomeres, leading to an increase in cell number without an increase in overall size. In human embryogenesis, this type of cleavage ensures proper cell distribution and organization, essential for subsequent developmental stages. The process allows the formation of a multicellular embryo and sets the foundation for the formation of various tissues and organs. This bilateral cleavage type is vital in establishing the early structure and symmetry in the developing human embryo, essential for healthy development.

In humans, the bilateral holoblastic cleavage pattern involves repeated mitotic divisions, producing a blastula consisting of numerous small, identical cells. These cells maintain totipotency, allowing them to differentiate into specialized cell types as development progresses. This process of cleavage ensures the formation of a multicellular structure, setting the stage for gastrulation and subsequent stages of embryonic development, ultimately leading to the formation of a complex organism like a human being. Thus option A is correct.