Simple histochemical stain for acrosomes on sperm from several species

The acrosome reaction is an exocytotic process that enables a sperm to pene trate the zona pellucida and fertilize an egg. The process involves the fen estration and vesiculation of the sperm plasma membrane and outer acrosomal membrane releasing the acrosomal contents. Many different methods have bee n developed to detect the acrosomal status of sperm. These techniques are s ometimes complicated, costly, and can be used on only a few species. The ai m of this study was to develop an efficient and inexpensive method to asses s the acrosomal status of sperm from a variety of species. We prepared and fixed sperm from humans, cattle, swine, rabbits, guinea pigs, and mice and stained them with Coomassie G-250. The acrosomes were stained intensely blu e in color. Following capacitation, some sperm were incubated for 1 hr with 10 mu M calcium ionophore A23187 to induce the acrosome reaction. They wer e also stained with Coomassie G250. Ionophore-treated sperm lacked Coomassi e staining over the acrosomal region. Differential interference contrast (D IC), bright field microscopy or Pisum sativum agglutinin staining confirmed that the acrosomes of sperm from these species were reacted in response to calcium ionophore treatment and the acrosome reaction frequencies matched results with Coomassie staining. These results demonstrate that the acrosom al status of mammalian sperm from several species can be determined easily and reliably using this simple Coomassie Blue G-250 staining method. (C) 19 99 Wiley-Liss, Inc.