Progesterone-Induced Acrosome Reaction: DISCUSSION(4)
In this scenario the sperm uncoating process of P-BSA-FITC-negative sperm cells was still not effective. An alternative explanation for the sperm cell population that remained negative for P-BSA-FITC or for C-262/RAM-FITC staining (after 5-h capacitation period; Figs. 5 and 6) is the possibility that they lack the progesterone receptor. However, this is unlikely, since after Percoll washing, most cells (> 95%) were positively stained for the progesterone receptor at the apical plasma membrane (Fig. 2B). buy cheap antibiotics
In fact, those cells were more sensitive to progesterone treatments than conventional washed cells (data not shown). The observed low percentage of sperm cells that stained positively for the progesterone receptor prior to incubation explains why progesterone cannot effectively induce the AR in freshly ejaculated stallion spermatozoa. Interestingly, it has been shown that the inability of spermatozoa to respond to progesterone in vitro might be related to male infertility. During the AR, sperm cells have a patchy apical P-BSA-FITC or C-262/RAM-FITC labeling (Fig. 1C). Deteriorated cells were labeled at the postacrosomal region (Figs. 1C and 3B).