Question

The 32 cell stage of the human embryo is
A) Smaller than the fertilized egg
B) Same size as the fertilized egg
C) Two times of the size of the fertilized egg
D) Four times of the size of the fertilized egg

Answer 1

Hint: Human embryogenesis or the process of human embryonic development deals with the development and formation of the human embryo. This process is characterised by cell division as well as cell differentiation throughout the early developmental stages.

Complete Answer:
A) Option a: The size of a fertilized egg is 32 cells which is equal to 32. Therefore, this is the incorrect option.

B) Option b: Fertilization results in the production of a diploid zygote which subsequently undergoes the process of cleavage division. This cleavage further results in increasing the overall cell number; however, the size still remains the same as that of the fertilized egg. Morula is a cell type which undergoes mitotic division thereby resulting in the production of around 32 cells. This 32-cell stage is thus referred to as blastula wherein all the cells are of the same size as that of the zygote. Therefore, this is the correct option.

C) Option c: Two times the size of fertilized egg means 64 cells which is greater than 32. Therefore, this is the incorrect option.

D) Option d: Four times the size of fertilized egg means 128 cells which is greater than 32. Therefore, this is the incorrect option.

Thus, the correct option is b) Equal to 32.

Note: The process of embryogenesis includes co-ordinated spatial and temporal modifications such as gene expression, growth of the cell, and cellular differentiation.