Ultrastructure of spermatogenesis in the hawaiian red lobster, Enoplometopus occidentalis (randall).

Electron microscopy of spermatogenesis in the Hawaiian red lobster, Enoplometopus occidentalis (Randall), has revealed unusual activity within membranous organelles. Mitochondria-like bodies (MLB-1) seen first in spermatogonia appear in primary spermatocytes to swell and fuse as the cytoplasm develops annulate lamellae and other membrane complexes. In early spermatids, annulate lamellae derived from the nuclear envelope contribute to development of an extensive lamellar membrane complex within the cytoplasm, the forerunner of the lamellar region. Other mitochondria-like bodies (MLB-2) originate from this membrane complex and contribute to formation of the acrosomal vesicle, which assumes a semicrystalline organization composed of bundles of tubular components slightly larger in diameter than microtubules. An amorphous subacrosomal material may be equivalent to the acrosomal tubule of other decapod spermatozoa. Centrioles at the base of the acrosome produce microtubules that extend between the membranes of the lamellar region distally through the uncondensed nucleus as the cores of the three radial arms of this aflagellate spermatozoon. Nuclear material and electron-dense lamellar region membranes project into the bases of these radial arms. Nuclear and plasma membranes are fused except where the acrosome lies between them. Of the mitochondria-like bodies, the MLB-1 do not persist into spermiogenesis, and the MLB-2 are derived from the lamellar region. This is in contrast with other reported studies of lobster spermatozoon ultrastructure.