Development of an in vitro oviduct epithelial explants model for studying sperm-oviduct binding in the buffalo

In this study, we developed an in vitro model for studying sperm-oviduct binding in the buffalo. Oviduct explants were prepared by overnight culture of epithelial cells in TCM-199 medium under 5% CO₂ at 38.5 °C. Cryopreserved spermatozoa from buffalo bulls (n = 4) were incubated with the oviduct explants, and the sperm-oviduct explants complex was stained with JC-1. The effect of sperm concentration (2, 3 and 4 million), size of the oviduct explants (<0.2, 0.2-0.3, 0.3-0.4 and >0.4 mm² ) and time of incubation (1 hr and 4 hr) on binding index (BI-number of sperm bound to unit area of explants) was studied. No significant difference was observed in the BI among <0.2, 0.2-0.3 and 0.3-0.4 mm² size of explants; however, the BI decreased significantly (p < .05) when the size of explants exceeded 0.4 mm² . The BI decreased significantly (p < .05) when the sperm concentration was increased to 4 million, while the duration of incubation did not have any significant effect on the BI. The interaction of bulls with explants size, sperm concentration and incubation time was not significant. The developed assay has the potential to be used as an in vitro model for studying sperm-oviduct binding in the buffalo.