The acrosome reaction in Bufo arenarum spermatozoa has been visualised only by electron microscopy. Different staining procedures for spermatozoa are described in the present study. By light microscopy the acorsomal status cannot be determined, In some reacted sperm, stained with Coomassie blue, a filament that could be the ‘perforatorium’ was observed, as seen by electron microscopy. Several fluorescent lectins were used, but only FITC-PNA binds to acrosomal proteins. However, the fluorescence observed was weak. Indirect immunofluorescence, with antibodies raised against acrosomal matrix, showed different staining patterns between acrosome-reacted and intact spermatozoa. The technique is specific for evaluating acrosomal status in a large population of spermatozoa. Moreover, immunostaining, in contrast with lectin staining, can be carried out in the presence of glycoconjugates such as oocyte extracellular matrix without interference.
