Question

Which is absent in human sperm?

• A. Endoplasmic reticulum
  
• B. Centriole
• C. Mitochondria
  
• D. Nucleus
  

Answer 1

The correct option is A Endoplasmic reticulum


Spermatozoa
Spermatozoa is a mature male gamete containing 23 chromosomes.
It possesses head, neck, middle piece and tail.

Nucleus
In spermatozoa, the nucleus contains the haploid set of chromosomes which carry the genetic information to the next generation. It is present in the head.

Mitochondria
Spermatozoa contains three centrioles as follows:

• The proximal centriole located towards the nucleus in the neck plays a role in the first cleavage of the zygote.
• Distal centriole in the neck, gives rise to the axial filament of the sperm which helps in the movement of the tail.
• Ring centriole at the end of the middle piece serves as a stabilizing structure for tail rigidity

Endoplasmic reticulum
Endoplasmic reticulum is absent in spermatozoa. During the transformation from spermatid to spermatozoa in spermiogenesis, endoplasmic reticulum is lost.

Final answer
(D) Endoplasmic reticulum