acrosome vesiculate, releasing the acrosomal contents (Austin & Bishop, 1958; Austin, 1963; Hadek, 1963; Piko & Tyler, 1964; Barros, Bedford, Franklin & Austin, 1967; Bedford, 1967b). The inner acrosome membrane then becomes the outer ensheathment of the sperm head. Under these circumstances, the contents of the compartment between the inner acrosome membrane and the nucleus may be important fo...