Spermiogenesis in Chalcides ocellatus tiligugu (Gmelin) (Squamata, Scincidae): An electron microscope study

Abstract

At the end of spermiogenesis in Chalcides ocellatus tiligugu the acrosomal complex is constituted by a homogeneous anterior cap derived from the acrosomal vesicle and by a paracrystalline posterior cap that arises from nuclear membrane proliferation. During the spermiogenetic process, the spherical nucleus becomes elongated and cylindrical in shape, and assumes a homogeneous appearance because its chromatine condenses. At the onset of spermatid elongation, a set of microtubules appears as a helix surrounding the nucleus. At the end of elongation, the microtubules become parallel to the main axis of the nucleus. From the early stage of spermiogenesis, the two centrioles (proximal and distal) and the flagellum are situated at the posterior pole of the nucleus. The two centrioles are encircled by the dense connecting piece, which is continuous with the nine accessory fibers surrounding the flagellum. At a later stage, the mitochondria form the mitochondrial sheath and four rings of electron‐dense material. In the first portion of the flagellum, between mitochondria and accessory fibers, a fibrous helix encircles the entire length of the flagellum. The spermatozoa mature completely eliminating their cytoplasm in the epididymal duct.

Key Words:

• Reptiles
• Testes
• Spermiogenesis
• Ultrastructure