Expression of CRISP proteins in the male equine genital tract

Cysteine rich secretory proteins (CRISPs) have been detected immunochemical ly in the equine male genital tract. CRISPs are secretory products of the e pididymis, the ampulla and the seminal vesicle. A particular feature of the horse is the abundance of CRISPs in seminal plasma. CRISPs can also be det ected in extracts of testicular, epididymal and ejaculated spermatozoa in i ncreasing amounts. Unlike other seminal plasma proteins, they cannot be rem oved completely from spermatozoa by high salt treatment. The remaining CRIS P antigens are localized on the midpiece, and the postacrosomal and equator ial region of the sperm head. Tissue distribution and localization of CRISP s on equine spermatozoa point to a role of these proteins in epididymal spe rm maturation and equine reproduction.