Acrosin activity of cryo-preserved human spermatozoa

The acrosin activity of human spermatozoa was determined in fresh, glycerolated, and cryo-preserved semen specimens. In 119 semen specimens, mean increases in acrosin activity of 62% in glycerolated and 56% in cryo-preserved samples were found. Thus, no statistically significant differences in mean acrosin activity were found between glycerolated and cryo-preserved spermatozoa. However, 23.5% of the cryo-preserved samples showed a significant decrease in extractable acrosin activity when compared with untreated controls. In oligospermic specimens (less than 40 million spermatozoa/ml), a statistically significant decrease in acrosin activity due to cryo-injury was detectable. Differentiation of specimens responding to glycerol pretreatment with an increase in extractable acrosin activity from those responding with a decrease showed a different freezing behavior, indicating two ejaculate types with respect to acrosin extraction. Samples frozen without glycerol protection showed the same amounts of extractable acrosin activity as did glycerol-protected specimens. The stability of acrosin in acidic acrosomal extracts during liquid nitrogen freeze treatment was confirmed.