Effects of HSPA8, an evolutionarily conserved oviductal protein, on boar and bull spermatozoa.

Previous studies have shown that a soluble protein fraction derived from preparations of apical plasma membrane (APM) of the oviductal epithelium enhances the in vitro survival of mammalian spermatozoa. Here, we show that the survival enhancing property of the soluble protein fraction seems to depend significantly upon heat shock 70 kDa protein 8 (HSPA8 previously known as HSPA10). The following findings in the present study enabled us to draw this conclusion: first, using proteomic analysis, we identified a subset of 70 kDa oviductal surface proteins that bound to spermatozoa, one of which was HSPA8.

Sperm selection and competition in pigs may be mediated by the differential motility activation and suppression of sperm subpopulations within the oviduct.

When spermatozoa from two or more boars are mixed and females inseminated, the resulting litters are often skewed in favour of one male but there is currently no satisfactory physiological explanation for this effect. However, to reach the oocytes, the spermatozoa must enter the oviduct where they are exposed to factors that modulate their activity. They either become sequestered within the oviductal sperm reservoir or bypass the reservoir and proceed towards the oocytes.