The exocytosis of acrosomal lysins and the extension of an acrosomal process
(or its equivalent as in chitons [Buckland-Nicks et al., 1988]) are typical of mechanisms used to penetrate the egg envelopes of free-spawning marine invertebrates; however, they may not always be necessary even when present (see discussion in Monroy and Rosati, 1983).
To find the retardance of a single actin filament, we divided the measured retardance of the acrosomal process
by its number of actin filaments (80).
Electron microscopic observations showed the acrosomal process
of sperm penetrating the oocyte by digesting the vitelline coat with sperm lysin (Fig.
When the sperm reach the outer chorion of the egg during fertilization (Nicander and Sjoden, 1971), or when they are exposed to fixatives (Jaana and Yamamoto, 1981), a long acrosomal process
Specificity of fertilization in crosses between several genera of urchins has been shown to result mainly from "primary gamete binding," the attachment of the sperm acrosomal process
to the egg vitelline layer, visualized by electron microscopy (Summers and Hylander, 1975).
The sperm of several marine bivalves including Spisula and Mytilus possess preformed acrosomal processes
that do not undergo a polymerization-driven elongation (Hylander and Summers, 1977; Longo, 1978a).