PROSTASOME-LIKE PARTICLES IN STALLION SEMEN

Human semen contains membranous vesicles called prostasomes. They are secreted by the prostate gland and contain large amounts of cholestero l, sphingomyelin, and Ca2+. Prostasomes enhance the motility of ejacul ated spermatozoa and are involved in a number of additional biological functions. No prostasome-like vesicles have been described in horse s emen up to now. We have demonstrated the presence of prostasome-like v esicles in the equine semen and characterized them as to size, morphol ogy, and lipid composition; we have found that they are similar to hum an prostasomes in many respects. We propose that these vesicles might be important for the fecundity of horse semen. This is of interest sin ce the success of artificial insemination is limited by the fact that stallion sperm barely survive cryopreservation.