Our flow cytometry analysis of the changes in sZP binding ability of individual cells within the live sperm population has revealed considerable heterogeneity between cells in their speed of response to IVF conditions. One subgroup of sperm underwent the changes relatively rapidly, within the first 60 min of incubation, whereas the rest of the population underwent the changes at disparate and much slower rates (or not at all, within the time-frame of our experiments). At all time points, two live subpopulations could be distinguished clearly; thus the change in zona binding ability within any given individual sperm could be deduced to be rapid. buy asthma inhaler
The heterogeneity in rate of various sperm responses to IVF conditions and the either/or characteristic of this response has been noted in previous studies (see ), as has been the increase in sperm death brought about by IVF conditions . While zona binding ability is not directly associated with membrane instability (compare effects of EGTA on these respective characteristics), the parallel enhancing effects of bicarbonate on both suggest that they may depend on a common core mechanism. It has been proposed that capacitation is necessarily a destabilizing process, and that the capacitated state represents a “window” degree of instability.