Abstract
The objectives of the present study are to characterize the motility and penetrability into zona-free hamster eggs of boar spermatozoa from 7 regions of the epididymis. Spermatozoa from the caput epididymidis were immotile or exhibited a flagellant or circular type of movement. However, 80% of the cells from the proximal cauda showed an intensive, forward movement. When the spermatozoa from each region of the epididymis were coincubated with zona-free hamster eggs after preincubation for inducing the acrosome reaction, they exhibited high penetration rates (95-100%) and average number of spermatozoa (3.4-5.8) in penetrated eggs irrespective of their origin. These findings indicate that most of the spermatozoa acquire the ability to exhibit progressive motility during their transit through the corpus, and that at least some of the cells located in the proximal caput have the ability to fuse with egg plasma membrane.
