**6. Regulation of sperm motility**

Sperm depicts two kinds of motility:

a.Progressive motility—typical for newly ejaculated sperm.

Spermatozoa acquire the ability of progressive motility in the epididymis. Relatively symmetrical motion of flagella which leads to forward movement has been shown in this type of motility [23].

b.Hyperactivated motility—after sometimes either in reproductive tract of female or in culture, sperm achieves the hyperactivated motility that is characterized by whip like beating of flagellum, asymmetrical flagellar bends and circular swimming [24].
