The epididymis is a mass of long, narrow, closely coiled tubules which lies along the inner side of each testis, and is differentiated into > upper caput epididymis or head; middle corpus 'epididymis or body and lower cauda epididymis or tail. In the head of the epididymis, the sperms undergo physiological maturation, acquiring increased motility and fertilizing capacity.
In the tail of the epididymis sperms are stored before entering the vas deferens.