Ultrastructural evidence of spermatogenesis in the rusty parrotfish, Scarus ferrugineus (Teleostei Scaridae)

This work analyses the spermatogenesis in the males of Scarus ferrugineus from histological and ultrastructural points of view. This study was carried out during the period of formation of spermatozoa thus being able to determine the pattern of spermiogenesis which is important for phylogenetic analysis. Histological examination revealed that the germ cells are classified into spermatogonia, spermatocytes, Sertoli cells, spermatids and spermatozoon based on morphology and size of the nucleus, organelles and centriolar morphology. Ultrastructural characteristics of primary spermatocytes show large nuclei with moderately compacted clusters of chromatin while secondary spermatocytes are comparatively smaller in size with central nuclei and scattered chromatin in either pole. The spermatozoon of this species is characterized by: the diplosome remains outside the nuclear fossa, the nucleus rotates at a slight degree and the flagellum is asymmetrically located, the two centrioles are arranged perpendicular to each other and no more than five spherical mitochondria are observed. Structural characteristics of Leydig cells and Sertoli cells were also described and discussed.