Post testicular sperm maturational changes in the bull: important role of the epididymosomes and prostasomes

Abstract

After spermatogenesis, testicular spermatozoa are not able to fertilize an oocyte, they must undergo sequential maturational processes. Part of these essential processes occurs during the transit of the spermatozoa through the male reproductive tract. Since the sperm become silent in terms of translation and transcription at the testicular level, all the maturational changes that take place on them are dependent on the interaction of spermatozoa with epididymal and accessory gland fluids. During the last decades, reproductive biotechnologies applied to bovine species have advanced significantly. The knowledge of the bull reproductive physiology is really important for the improvement of these techniques and the development of new ones. This paper focuses on the importance of the sperm interaction with the male reproductive fluids to acquire the fertilizing ability, with special attention to the role of the membranous vesicles present in those fluids and the recent mechanisms of protein acquisition during sperm maturation.

Figure 1

Photography taken from a bull epididymis. Different anatomical sections are identified: caput (b), corpus (c), and cauda (d). Vas deferens is also indicated (e). Reproduced from [16] with permission of the Editorial.

Figure 2

Schematic representation of apocrine secretion in principal cells of the epididymis. The inset shows electron micrograph of epididymosomes. AB, apical bleb; EP, epididymosomes; ILC, intraluminal compartment; MV, microvilli. Reproduced from [32] with permission of the Editorial.