Presence of Microfilaments and Tubular Structures in Boar Spermatozoa after Chemically Inducing the Acrosome Reaction

Abstract

The addition of the calcium ionophore A23187 and calcium to washed ejaculated boar spermatozoa initiates acrosomal membrane-plasma membrane fusion and vesiculation in about 9O% of treated cells. Microfilaments measuring 5–9 nm form in the area of vesiculation and along unvesiculated plasma membrane. Microtubular-like structures are found associated with the inner acrosomal membrane in the area of vesiculation of acrosome reacted sperm. In a small percent of cases, the plasma membrane is removed in treated and untreated spermatozoa. In these sperm, microtubular-like structures are either associated with the equatorial segment of the acrosome or lie between the postacrosomal sheath and the nuclear membrane.