The kinetics and possible mechanism of acrosomal process
The acrosome reaction consists of two steps--polymerization and lengthening of the acrosomal process
with subsequent exocytosis of the acrosomal vesicle, which exposes bindin; bindin then coats the acrosomal process
and aids in sperm-egg attachment and fusion.
In many invertebrates, acrosomal exocytosis of spermatozoa starts with membrane fusion at the apical point and produces an acrosomal process
(Dan, 1967; Morisawa et al.
The polymerization of actin: its role in the generation of the acrosomal process
of certain echinoderm sperm.
Firstly, there is no extrusion of an acrosomal process
or "perforatorium" by the polymerization of actin, as occurs throughout molluscs and other metazoan groups (see review by Tilney, 1985).
Simultaneous with the exocytosis of lysins is the rapid extension of an acrosomal process
that projects the inner acrosomal membrane into contact with the vitelline layer overlying the egg microvilli.
In the meantime, the acrosomal process
and the sperm tail had gradually acquired a yellowish-orange fluorescence which became stronger with time over the next several minutes (top to bottom panels).
Limulus sperm shows two types of discharge of acrosomal process
-- true (Fig.