NEETZoologyHuman Reproduction
The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This entry immediately induces which of the following cellular events?
Options
- ACompletion of the meiotic division of the secondary oocyte, forming a second polar body and an ootid
- BCompletion of the first meiotic division of the primary oocyte, forming the first polar body
- CInitiation of the first cleavage division to form a two-celled zygote
- DBreakdown of the germinal vesicle and release of the secondary oocyte from the follicle
Correct answer
A. Completion of the meiotic division of the secondary oocyte, forming a second polar body and an ootid
Step-by-step solution
According to NCERT, the entry of a sperm into the cytoplasm of the ovum through the zona pellucida and the plasma membrane induces the completion of the meiotic division of the secondary oocyte. This second meiotic division is unequal and results in the formation of a second polar body and a haploid ovum (ootid). The first meiotic division is completed prior to ovulation inside the tertiary follicle, making the second option incorrect. Cleavage divisions begin only after the fusion of the male and female pronuclei