Fig.1.
 Transverse section through the apex of a spermatozoon in the perivitelline space. Apical processes protrude from the apex of the head. Connections are recognized between the base of apical processes and the nuclear membranes.
AP, apical process; ES, egg surface.

Fig.2.
 Sagittal, slightly oblique,section through the apex of a spermatozoon in the perivitelline space. Apical processes(arrows) protrude from a region which is fairly distant from the place where the acrosome was.
AS,apical substance.

for details: Fukumoto, Invert. Reprod. Develop. 17, 147-154 (1990)

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