Sperm becomes mobile in: March 2008

Ans. D: EpididymisSpermatozoa leaving the testes are not fully mobile. They continue their maturation and acquire motility during their passage through the epididymis.Motility is obviously impoant in vivo, but feilization occurs in vitro if an immotile spermatozoon from the head of the epididymis is microinjected directly into an ovum.The ability to move forward (progressive motility), which is acquired in the epididymis, involves activation of a unique protein called CatSper, which is localized to the principal piece of the sperm tail.