Due to technical limitations, it is difficult to follow this process in situ. In this study, we used biotinylated carbohydrate probes to detect carbohydrate affinity of sperm cells before and after capacitation in vitro. To this end, the specific oviduct-binding area of the sperm surface (the apical sperm head plasma membrane) with the carbohydrate binding ligands was isolated. With this approach, we were able to quantify affinity and binding capacity of bovine sperm cells for various carbohydrate probes.
We were also able to study carbohydrate-binding competition of unlabeled sugar moieties (including heparin and GAG from follicular fluids) using these materials. The monitored effects of in vitro capacitation of bovine sperm on carbohydrate-binding characteristics may well relate to those occurring during in vivo capacitation of sperm cells. It is likely that the altered carbohydrate-binding properties of capacitating bovine sperm cells at least partly represent alterations of sperm surface molecules involved in sperm-oviduct interaction.