7. L. Castellani Ceresa, M. F. Brivio, G. Radaelli. Electron Microscopic Localization of F actin in Acrosome Reacted Boar Spermatozoa by Means of a Phalloidin FITC Complex. J. Submicrosc. Cytol. Phatol., 23, n\ub02, 347 349, 1991.An immunocytochemical study at the ultrastructural level has been performed in boar spermatozoa in order to clarify the aggregation state of actin before and after the acrosome reaction. A new phalloidin probe has been used to detect F-actin: a phalloidin derivative conjugated with FITC, followed by incubation with an anti-FITC antibody. The protein A-gold technique was then applied for the localization of the antigenic sites. Gold particles were localized on the sperm surface only after the acrosome reaction which was induced by the ionophore A23187
