Gametogenesis and reproductive cycle of Melanorivulus aff. punctatus (Boulenger, 1895) (Cyprinodontiformes, Rivulidae) in Chapada dos Guimarães, Mato Grosso, Brazil

Abstract

The comprehension of the reproductive cycle allows to understand which are the morphological changes that develop in the gonad during this interval. Thus, many studies have been undertaken in order to describe and classify the stages of gonadal development and reproductive status of Neotropical fishes. For this purpose, specimens of Melanorivulus aff. punctatus were collected in a permanent dam in Chapada dos Guimarães, Mato Grosso, Brazil. The gonads were prepared for analysis by light microscopy. The oogenesis and spermatogenesis have been described, characterizing the stages of gonadal development, together with assessments of the gonadosomatic ratio, germ cell count and verification of variation of mature oocytes in females. Throughout the year the male gonads presented themselves as capable of reproducing, characterized by the presence of undifferentiated and differentiated spermatogonia, spermatocytes organized into cysts, spermatids in cysts whose wall was thicker and the spermatozoa was free in the lumen and the duct. This can indicate a continuous reproductive cycle with split spermiation. The females had gonads in the development stage from May to September with undifferentiated and differentiated oogonias and early oocytes always facing the lumen, abundant pre-vitellogenic and vitellogenic oocytes and some atresias. In the phase capable of spawning, observed from October to March, the mature oocytes are abundant, there are many post-ovulatory complexes and some atresia in advanced stage. The regression, observed in some individuals from February to April, is characterized by ovaries with many atresias and post-ovulatory complexes. The same results were found in the quantitative assessments. Therefore, it may be characterized as discontinuous cycle with split spawning. Thus, the reproductive cycle of this species can be characterized as continuous for males and discontinuous for females, which have a most intense phase of reproduction from October to March. However, both have fractional release of gametes.A compreensão do ciclo reprodutivo possibilita entender quais são as mudanças morfológicas que se desenvolvem na gônada neste período. Assim, muitos estudos têm sido realizados no intuito de descrever e classificar as fases de desenvolvimento gonadal e dos estados reprodutivos dos peixes da região Neotropical. Com esse objetivo foram coletados espécimes de Melanorivulus aff. punctatus em um represamento permanente em Chapada dos Guimarães, Mato Grosso, Brasil. As gônadas foram preparadas para análise à microscopia de luz. A ovogênese e a espermatogênese foram descritas e caracterizados os estágios de desenvolvimento gonadal, juntamente com as avaliações de razão gonadossomática, contagem de células germinativas e verificação de variação de ovócitos maduros em fêmeas. Durante todo o ano as gônadas masculinas apresentaram-se como aptas a reprodução, caracterizadas pela presença de espermatogônias indiferenciadas e diferenciadas, espermatócitos organizados em cistos, espermátides em cistos com parede mai...

Histochemistry of the zona pellucida of the ovary of a species with natural polyovulation: Lagostomus maximus (Rodentia, Hystricomorpha, Chinchillidae)

“…In the present study, we investigated the histochemical characteristics of the ZP of the ovarian follicles of Lagostomus maximus , and its variations in NPr and Pr females, using histochemical and lectin histochemical techniques. The results, obtained at the ZP using the histochemical PAS and AB at different pH techniques, do not differ from those described by studies carried out in other mammals species, such as Mus musculus (Kaufman, Fowler, Barratt, & McDougall, ; Shimizu & Yamada, ), Mesocricetus aureatus (Delgado & Zoller, ), Sus scrofa scrofa (Parillo, Diverio, Todini, & Fagioli, ), Melanorivulus punctatus (Cassel, Mehanna, Mateus, & Ferreira, ) and even in other hystricomorphic rodents such as Myocastor coypo (Felipe, Cavodevila, & Callejas, ). The α‐amylase‐PAS, K(OH)/PA*/Bh/PAS and PA/Bh/KOH/PAS techniques were used to study the presence of sugars, usually in organs that produce different types of mucins, since they allow differentiating certain features of a specific portion of carbohydrates (Lev & Spicer, ; McManus, ; Pearse, ; Reid, Culling, & Dunn, ; Volz, Reid, Park, Owen, & Dunn, ).…”

Desiccation plasticity in the embryonic life histories of non-annual rivulid species

“…These non-annual species commonly inhabit shallow areas of streams and swamps and their embryos generally develop in stable aquatic conditions [ 37 ]. Data of a few species suggest that they are continuous breeders [ 38 , 39 ]. It has been repeatedly suggested that diapause also occurs in some species of Rivulus [ 40 , 41 ], but the evidence is indirect and it remains to be verified in the controlled and standardized conditions used, for example, by Wourms [ 25 , 26 ].…”

Permanent germinal epithelium and reproductive cycle of tropical gar Atractosteus tropicus males (Lepisosteiformes: Lepisosteidae), Tabasco, Mexico

“…It should be noted that restricted spermatogenesis is the evolution of the Sertoli cell/spermatid association, resulting in the formation of spermatozeugmata or spermatophores present in C. undecimalis, Melanorivulus aff. punctatus, Poecilia latipinna, Goodea atripinnis, Ilyodon whitei, and Cichlasoma dimeru (Grier, Linton, Leatherland, & Vlaming, 1980;Pudney, 1995;Grier & Taylor, 1998;Uribe et al 2010;Rey, Da Cuña, Meijide, & Guerrero, 2012;Cassel, Mahmoud, Lúcia, & Adelina, 2013). Spermatogenesis in A. tropicus is a dynamic process in which spermatogonia go through several development stages to form spermatozoa.…”