Type 1: A small proacrosomal vesicle appears in the blister of early spermatid, which becomes larger during spermiogenesis forming a single acrosome.
Type 2: Multiple proacrosomal vesicles appear in a blister at the early spermatid. These proacrosomal vesicles fuse with each other during spermiogenesis thereby transforming into a single acrosome.
Type 3: Multiple acrosomal vesicles appear in a blister of an early spermatid. These proacrosomal vesicles transform into multiple acrosomal vesicles whithout coalescing with each other.
A. blister of an early spermatid;
B. blister of a middle stage spermatid;
C. sagittal view of the apex of a differentiated sperm;
C'. frontal view of a differentiated sperm; Std, spermatid.
for details: J.Morph.242:101-106 (1999)
