Estrutura fina do espermatozóide de Acestrorhynchus falcatus Bloch (Teleostei, Characidae) da região norte do Brasil

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

“…The resulting spermatozoon, an aquasperm, has no acrosome, a head containing a spherical nucleus, a midpiece of variable dimensions with or without a cytoplasmic channel, and a long flagellum (Jamieson, 1991;Mattei, 1991). Nuclear rotation during spermiogenesis has been observed in all examined species of the Curimatidae, and apparently occurs in almost all other Characiformes whose spermatozoa have been described, with the exception of Acestrorhynchus falcatus (Matos et al, 2000) and Mimagoniates barberi (Pecio & Rafinski, 1999). In spermatozoa of the Curimatidae, the nucleus is spherical (Matos et al, 1998;present paper) as in other species of Characiformes with external fertilization (Jamieson, 1991;Mattei, 1991;Quagio-Grassiotto et al, 2001).…”

“…The chromatin may also be seen in clusters in some members of the family Characidae (Matos et al, 1993;Aires, 1998;Burns et al, 1998;Romagosa et al, 1999;Zaiden, 2000;Veríssimo-Silveira, 2003). Among other members of the Characiformes, spermatozoa generally exhibit thick fibers of homogeneously condensed chromatin (Jamieson, 1991;Mattei et al, 1995;Burns et al, 1998;Magalhães, 1998;Matos et al, 1998;Pecio & Rafinski, 1999;Matos et al, 2000;Andrade et al, 2001;Quagio-Grassiotto et al, 2001).…”

“…A medial and shallow nuclear fossa, represented by a slight depression in the nuclear outline, is observed in spermatozoa of Citharinus sp., Citharinidae (Mattei et al, 1995). In some members of the Characidae (Bryconinae and Salmininae) the nuclear fossa is deep (Aires, 1998;Romagosa et al, 1999, Zaiden, 2000Veríssimo-Silveira, 2003) while in others (Cheirodontinae) as well as in the family Acestrorhynchidae, the nuclear fossa is absent (Burns et al, 1998;Matos et al, 2000).…”

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

“…The spermatic characteristics of chromatin condensation found in citharinids (Mattei et al, 1995) is similar to that found in Chanos chanos, a gonorynchiform (Gwo et al, 1995), sister group of the Otophysi, and in Olivaichthys mesembrinus, Diplomystidae (Quagio-Grassiotto et al, 2001b), the most basal family in Siluriformes, and may represent a primitive state of the character that remains in some representatives of characiforms, including serrasalmines, Salminus, Brycon, stevardiines, anostomids, prochilodontids, and cynodontids. Among non-characid characiforms for which information is available, the large floccus of fibrous chromatin is not present in any other family of the Suborder Characoidei (Matos et al, 2000;Quagio-Grassiotto et al, 2001a;Veríssimo-Silveira, 2007). 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.…”

“…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).…”