Morphofunctional changes of female germinal epithelium to support spermatozoa along the annual reproductive cycle in an inseminating catfish (Trachelyopterus galeatus, Auchenipteridae)

Abstract

The reproductive system of some fish species presents elaborate mechanisms by which the females store spermatozoa inside their ovaries, keeping them viable for fertilization for an extended period of time. However, as intriguing as this sperm storage is, it is not yet understood how the sperm can remain viable in the ovary. Aiming to understand this phenomenon, the epithelium covering the ovarian lamellae, that is, the germinal epithelium, of the Cangati (Trachelyopterus galeatus), an inseminating catfish, was evaluated taking into account the different stages of the annual reproductive cycle. The germinal epithelium morphology changed during the annual reproductive cycle, presumably in preparation to receive the spermatozoa and keep them viable until fertilization. There was a progressive increase of the epithelium height. Also the number of intercellular junctions, desmosomes, and extended tight junctions, apparently increased forming chains that could be regarded as a barrier to isolate the sperm from the female immune system. Synthetic organelles were active releasing cytoplasmic granules and secretion in the epithelial enfolds in which the spermatozoa were deeply embedded. Concomitantly, oogonium nests were formed in the germinal epithelium during early folliculogenesis.

Characterization of short‐term storage of the semen ofTrachelyopterus galeatus(Siluriformes: Auchenipteridae) incorporating dimethylsulphoxide (dmso) to the diluent

“…For teleosts, sperm concentration can vary between 2 × 10 6 and 6.5 × 10 10 ml −1 (Leung, & Jamieson, 1991). In this study, sperm concentration was considered low (2.7 ± 0.7 × 10 6 ml −1 ), and the reproductive aspect of T. galeatus may be directly related to this parameter, because insemination is internal, that is, reproduction is achieved by copulation (Chiarini-Garcia et al, 2014).…”

Reproduction and fecundity of invader of internal insemination Trachelyopterus galeatus in a Neotropical floodplain

“…The spermatozoa of T. galeatus have elongated heads and may be free in the ovarian lumen or attached to the ovarian lamellae organized in groups forming spermatozeugmata. This represents an important strategy to maintain the viability of the spermatozoa for long periods (Melo et al, 2011;Chiarini-Garcia et al, 2014).…”

“…Fish with indeterminate fecundity release eggs in batches over an extensive reproductive season (Vazzoler, 1996;Lowerre-Barbieri, 2009). Reproductive aspects of these species were studied by Melo et al (2011), Chiarini-Garcia, Vieira, andGodinho (2014) and Lemes et al (2016), who show reproductive characteristics that allow the maintenance of the viable male gametes stored by the female until the moment of fertilization. Therefore, this study intends to: i) characterize gametogenesis through light microscopy and verify the reproductive phases of this species based on this information; ii) estimate oocyte diameter and verify if oocyte development is synchronous (determinate fecundity) or asynchronous (indeterminate fecundity); iii) verify the reproduction sites in the Paraná, Baía, and Ivinheima rivers; iv) estimate batch fecundity by gonad weight, total length, and total weight of the fish.…”

Coaves Kids: Clube De Observadores De Aves Infantil De Sorocaba (Sp)

“…Elofsson et al, (2006) demonstraram que a passagem dos espermatozoides pelo fluido ovariano de Gasterosteus aculeatus prolongou a motilidade de aproximadamente 1 minuto para várias horas, mas a fertilização só aconteceu no meio externo. Tais evidências mais a ausência de estudos registrando a fertilização dos oócitos, assim como a observação de oócitos fertilizados para as espécies de Auchenipteridae (MEISNER et al, 2000;PARREIRA et al, 2009;SANTOS et al, 2014;GODINHO. 2014), corrobora com a nossa hipótese de que a inseminação nos auchenipterideos pode corresponder a uma associação gamética interna, atuando na capacitação dos espermatozoides, mas que a fertilização pode ocorrer apenas quando a fêmea liberar os espermatozoides e os oócitos vitelogênicos no meio aquático.…”