Spermiogenesis and spermatozoa ultrastructure in five species of the Curimatidae with some considerations on spermatozoal ultrastructure in the Characiformes

Abstract

Spermiogenesis in the curimatid species, Steindachnerina insculpta, Cyphocharax gillii, C. modestus, C. spilotus, and Potamorhina altamazonica, is characterized by lateral development of the flagellum, nuclear rotation, eccentric nuclear fossa formation, and chromatin compacted into thick fibers. These spermatozoa exhibit a spherical head containing a nucleus with the chromatin highly condensed into thick fibers with small electron-lucent areas, and no acrosome. The nuclear fossa is of the moderate type and eccentric and penetrated by the centriolar complex. The midpiece is small, has many elongate vesicles, and a short cytoplasmic channel. Mitochondria may be elongate, branched or C-shaped, and are separated from the initial segment of the axoneme by the cytoplasmic channel. The flagellum contains the classical axoneme structure (9+2) and has a membranous compartment in the initial region; it does not have lateral fins. Only small differences were observed among the analyzed species and genera of the Curimatidae. Spermiogenesis and spermatozoa in the Curimatidae have many of the characteristics found in almost all other characiform species. On the other hand, the presence of a membranous compartment in the initial region of curimatid flagella, a structure common in many Cypriniformes spermatozoa, is unknown in other characiforms. Spermiogenesis and the spermatozoa of the Characiformes are discussed.

Comparative analysis of spermiogenesis and sperm ultrastructure in Callichthyidae (Teleostei: Ostariophysi: Siluriformes)

“…A similar characteristic was also observed in Trichomycteridae, other members of Loricarioidea (our unpublished data), and in Characiformes of the family Curimatidae (Quagio-Grassiotto et al, 2003).…”

“…In the Callichthyinae, sperm production occurs completely within spermatocysts in the germinal epithelium, characterizing this spermatogenesis as the cystic type. This type of spermatogenesis is present in most Teleostei (Mattei et al, 1993;Quagio-Grassiotto et al, 2001;Quagio-Grassiotto et al, 2003;Quagio-Grassiotto et al, 2005).…”

Spermiogenesis and spermatozoa ultrastructure in the Serrasalminae (Ostariophysi: Characiformes) with further evidence on the relationships of the piranhas and pacus

“…Calcagnotto et al (2005) postulated serrasalmines as a family and sister group to a monophyletic clade composed by the Anostomidae, Chilodontidae, Prochilodontidae, Hemiodontidae, and Parodontidae. Interestingly, serrasalmines, anostomids and prochilodontids share the presence of large floccus of fibrous chromatin, although it is not found in other studied Anostomoidea (families Curimatidae - Matos et al, 1998;Quagio-Grassiotto et al, 2003;and Chilodontidae -Pecio, 2003). However, the possible plesiomorphic nature of the chromatin condensation does not permit to consider the spermatozoa ultrastructure as a support for the hypothesis of a close relationship between anostomids and serrasalmines.…”

“…Spermiogenesis and spermatozoa types, organell distribution and other particularities of the spermatic structure, have been found to be highly conservative in a given lineage at family or subfamily level, making them useful for phylogenetic analysis (Baccetti et al, 1984;Jamieson, 1991;Mattei, 1991;Burns et al, 1998;Quagio-Grassiotto et al, 2003). Regarding the Characiformes, and particularly the Characidae, the available information is still scarce considering the large diversity of the group (Jamieson, 1991;Matos et al, 1993Matos et al, , 1998Matos et al, , 2000Burns et al, 1998;Magalhães, 1998;Pecio & Rafinski, 1999;Romagosa et al, 1999;Aires et al, 2000;Zaiden, 2000;Andrade et al, 2001;Quagio-Grassiotto et al, 2001aAmaral, 2003;Cruz-Landim et al, 2003;Pecio, 2003;Azevedo, 2004;Pecio et al, 2005Pecio et al, , 2007Weitzman et al, 2005;Veríssimo-Silveira et al, 2006).…”

Comparison of spermiogenesis in the externally fertilizing Hemigrammus erythrozonus and the inseminating Corynopoma riisei (Teleostei: Characiformes: Characidae)

“…However, some information on spermiogenesis is available for several other families belonging to the order Characiformes, including Erythrynidae (Quagio-Grassiotto et al, 2001), Curimatidae (Quagio-Grassiotto et al, 2003), Anostomidae (Pecio, 2003) and Alestidae (Shahin, 2006).…”