Espermiogênese em Eupemphix nattereri (Anura, Leiuperidae): aspectos ultra-estruturais

Abstract

ABSTRACT. Spermiogenesis in Eupemphix nattereri (Anura, Leiuperidae): ultrastructural aspects. Spermatozoon maturation involves an extense and complex process beginning with proliferation and differentiation of spermatogonia, passing through meiosis, and ending with spermiogenesis. The later event involves morphological and biochemical changes in order to transform spermatids into spermatozoa. Ultrastructural aspects of the spermiogenesis and testicular spermatozoa of the anuran Eupemphix nattereri (Steindachner, 1863) were analyzed by transmission electron microscopy. Spermiogenesis involves chromatin condensation and nuclear elongation, with visible cytoplasmic elimination. At this stage, a large amount of microtubules and glycogen can also be seen in Sertoli cell cytoplasm, surrounding each spermatid. The spermatozoon is fusiform and the acrossome forms a cap in the anterior region of the nucleus. A mitochondrial sleeve is found around the proximal portion of the tail. The tail presents an axonema with a 9+2 pattern, a justaxonemal fiber, an undulating membrane, and the absence of axial rod. This organization shows some similarities with species of the genus Physalaemus (Leiuperidae) such as P. biligonigerus (Cope, 1861), P. gracilis (Boulenger, 1883) and P. fuscomaculatus (Steindachner, 1864).KEYWORDS. Anura, Eupemphix nattereri, ultrastructure, spermiogenesis, spermatozoon. RESUMO.A maturação dos espermatozóides envolve um extenso e complexo processo que começa com a proliferação e diferenciação das espermatogônias, passa pela meiose e finaliza com a espermiogênese. Nessa fase, eventos envolvendo alterações morfológicas e bioquímicas transformam espermátides em espermatozóides. Aspectos ultra-estruturais da espermiogênese e do espermatozóide do anuro Eupemphix nattereri (Steindachner, 1863) foram analisados através de microscopia eletrônica de transmissão. A espermiogênese envolve condensação da cromatina e alongamento nuclear, com visível eliminação de citoplasma. Nesse estágio, grande quantidade de microtúbulos e glicogênio podem ser visualizados no citoplasma das células de Sertoli, rodeando cada espermátide. O espermatozóide é fusiforme e o acrossomo forma uma capa na região anterior do núcleo. A bainha mitocondrial é encontrada ao redor da porção proximal da cauda. A cauda apresenta o axonema com o modelo 9+2, uma fibra axonemal, a membrana ondulante e ausência de bastão axial. Esta organização apresenta algumas similaridades com espécies do gênero Physalaemus (Leiuperidae) como P. biligonigerus (Cope, 1861), P. gracilis (Boulenger, 1883) e P. fuscomaculatus (Steindachner, 1864).

A comparative ultrastructural analysis of spermatozoa in Pleurodema (Anura, Leptodactylidae, Leiuperinae)

“…However, Garda et al () proposed the homology of the subacrosomal cone with the conical perforatorium. We agree with their arguments, as well as other recent papers (e.g., Aguiar‐Jr et al, 2003, , 2006; Garda et al ; Zieri et al ). Transverse striations at midpiece : (0) absent, (1) present.…”

“…The ultrastructure of spermatozoa has been described in eighteen species of Leiuperinae: Engystomops pustulosus (as Physalaemus pustulosus , Scheltinga, ), Physalaemus biligonigerus , P. gracilis , P. marmoratus (as P. fuscomaculatus , Amaral et al, ), P. nattereri (as Eupemphix nattereri , Zieri et al, ), Pleurodema thaul (Pugin and Garrido, ), Pseudopaludicola falcipes (Amaral et al, ), and Pseudopaludicola ameghini , P. atragula , P. canga , P. facureae , P. giarettai , P. mineira , P. mystacalis , P. saltica , P. ternetzi , Pseudopaludicola sp. 1, and Pseudopaludicola sp.…”

Morfohistología testicular de Ceratophrys ornata (Bell) (Amphibia, Anura, Ceratophryidae)

“…El análisis de los testículos observados indica que los cinco ejemplares estaban en la misma etapa gametogénica y muestran características macroscópicas e histológicas similares a las observadas en otras especies de anfibios anuros neotropicales (Oliveira et al, 2002;Jamieson, 2003;Oliveira & Zieri, 2005;Zieri et al, 2008;Carezzano & Cabrera, 2010). El hecho de exhibir lóculos con todas las células del linaje espermatogénico lo que indicaría que presentan ciclos continuos.…”

Ultrastructure variation in the spermatozoa of Pseudopaludicola frogs (Amphibia, Anura, Leptodactylidae), with brief comments on its phylogenetic relevance

“…The subacrosomal cone observed in Pseudopaludicola has also been found in other Leiuperinae species, such as Physalaemus biligonigerus , P. gracilis (Amaral et al, ), P. marmoratus (= P. fuscomaculatus in Amaral et al, ), and P. nattereri (= E . nattereri in Zieri et al, ). However, this structure was absent in the leiuperine Pleurodema thaul (Pugin‐Rios, ) and in the leptodactilines Leptodactylus wagneri (Scheltinga, ) and Leptodactylus podicipinus (Salles, 2014).…”

“…Transversal striations found on the initial portion of the tail of the spermatozoa analyzed in this study are similar to the structures described in three Physalaemus species by Amaral et al (), as well as P. falcipes (Amaral et al, ) and P . nattereri (Zieri et al, ). These striations have also been observed in the male gametes of anurans of other families, such as Odontophrynus cultripes (Báo et al, ), as well as some rodents (Fawcett and Phillips, ).…”