Microtubular structures associated with the acrosome during spermiogenesis in the water-strider, Gerris remigis (say)

The ultrastructural organization of the acrosome during the course of spermiogenesis in the water-strider, Gerris remigis, has been studied in the electron microscope. The acrosome, which in the mid-spermatid is spherical and about 6–8 μ in diameter, becomes extremely elongated, until in the spermatozoon it is an attenuated, tapering rod measuring more than 2.5 mm in length. During this change in form, a system of parallel tubules appears within the acrosome. These acrosomic tubules measure about 130 Å in diameter, are present throughout the length of the acrosomal structure, and are probably responsible for its rigidity. A second system of microtubules, which have been preserved only with aldehyde fixatives, surrounds the acrosome. They are about 220 Å in diameter, and extend from a point near the insertion of the flagellum to about the midpoint of the acrosome. These cytoplasmic microtubules may also participate in maintaining the rigidity of the acrosome, and may be involved in the transport of newly synthesized protein and polysaccharide.