Asthenozoospermic stallions tend to have high acrosome reacted spermatozoa as evidenced by dual fluorescent staining assay

Abstract

Acrosome intactness of spermatozoa is the critical factor for establishing sperm reservoir in oviduct and for fertilizing an oocyte. However, frozen thawed spermatozoa tend to show higher proportion of acrosome reacted spermatozoa thereby compromising the fertility. Conventional staining techniques identify only sperm acrosome integrity and not precisely the acrosome reaction status. In this context, the current study was conducted to assess the acrosome status of cryopreserved spermatozoa using Fluorescein isothiocyanate conjugated peanut agglutinin and propidium iodide (FITC-PNA+PI) in stallions with varying sperm motility. Stallions were classified into high- (≥45%) and low-motile group (≤30%) based on their post-thaw sperm motility. The proportion of live acrosome intact (LAI) spermatozoa was significantly higher in high-motile group as compared to low-motile group. A significant positive correlation was observed between LAI and post-thaw sperm motility. In conclusion, the present study showed that FITC-PNA+PI combination could be used for rapid and accurate assessment of acrosome reaction status of stallion spermatozoa, and the proportion of LAI population in cryopreserved stallion semen had a strong correlation with sperm motility.