9, black bars), most sperm still exhibited a normal head bearing acrosomal vesicles with no anterior projections.
Acrosome reaction in abalone sperm involves the exocytosis of the acrosomal vesicle and the polymerization of subacrosoreal materials, composed mainly of actin, to form the anterior spike called acrosomal process (Neill & Vacquier 2004).
Store-operated calcium channels trigger exocytosis of the sea urchin sperm acrosomal vesicle.
Finally, the acrosomal tube grows very much and covers the primary and secondary acrosomal vesicles, the axial rod and the periaxial sheath.
It is placed in the cellular nucleus apix and presents several parts: primary acrosomal vesicle, secondary acrosomal vesicle, axial rod and capitullum, acrosomal tube and periaxial sheath (Fig.
The acrosome originates on the spermatide base, the first part to be formed is the primary acrosomal vesicle, which grows and projects, pushing the spermatide plasmatic membrane (Anderson et al.
However, there was a significant decrease in sperm entry into the cytoplasm after binding by sperm that had lost their acrosomal vesicles
prior to binding.
At an early stage of spermiogenesis, spherical acrosomal vesicles were found in a shallow depression of the nucleus (Fig.
Microtubules were regularly and diagonally arranged in the periphery near the acrosomal vesicles (Fig.
6), the acrosomal vesicles acquired a mature bell shape (Fig.
As in higher vertebrates, the bell-shaped acrosomal vesicle covers the apical portion of the nucleus, although it covers only a very limited region (Morisawa, 1995).
On the cytoplasmic side, the acrosomal vesicle
is slightly invaginated (Fig.