Effects of extenders and cryoprotectants on stallion sperm head morphometry

摘要

Researchers believe that sperm chromatin structure can be altered during cryopreservation, inducing a reduction in the surface area of sperm [1]. Furthermore, cryopreservation appears to reduce the ability of sperm chromatin to decondense [2]. It may be possible that the observed reduction of sperm surface area may ultimately be manifested in abnormal morphology of the sperm head [3]. One recent study has also associated abnormal chromatin structure with a reduction in stallion fertility [4]. Whereas cryopreservation of spermatozoa has been found to affect chromatin structure and surface area of the sperm head, these changes have not been evaluated morphometrically [3]. The overall metric dimensions of the sperm head (width and length) have been correlated with fertility in humans [5]. Commercial automated sperm morphometry analyses (ASMA) systems have been shown to be accurate and precise in measuring the dimensions of sperm head of a number of species including stallions [6,7]. In addition, applying the techniques of ASMA and multivariate cluster analyses [6], it was possible to determine discrete subpopulations of sperm head dimensions in fertile and subfertile stallions accurately. Thus, the present study was designed to study the effects of extenders and cryoprotectants on stallion sperm head morphometry using ASMA.