Spermatogenesis in Animal as Revealed by Electron Microscopy XXIX. Researches on the Development and Function of the Acrosomal Cap of the Grasshopper Acrida lata Motschulsky

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The acrosome of the grasshopper, Acrida lata Motsuchulsky, consists of an acrosomal cap, two acrosomal arms and a subacrosomal rodlet. The two acrosomal arms 5.0 μm in length and 100 nm in width run along the bilateral sides of maturing spermatid. The subacrosomal rodlet 5.0 μm in length and 220 nm wide is lodged in the electron-lucent acrosomal groove deeply housing the nucleus. When the spermatid juts out into the intercellular space between the nutritive cell and spermatid in an early stage of spermiogenesis, the acrosomal granule is enclosed with the dense acrosomal cap 43-57 nm thick which might originate from the Golgi complex of the nutritive cell. This docking-like phenomenon seems to be similar to the receptor-specific mechanism. On the basis of the results of serial sections, it is concluded that the acrosomal cap of developing spermatids may be a supporting apparatus for the long cone-shaped spermatid, since the cap is connected either with the plasma membrane or with the similar cap of an adjacent spermatid.