Female germ cell renewal during the annual reproductive cycle in Ostariophysians fish

Abstract

The objective was to characterize female germ cell renewal during the annual reproductive cycle in two species of ostariophysian fish with distinct reproductive strategies: a siluriform, Pimelodus maculatus, in which oocyte development is group synchronous and the annual reproductive period is short; and a characiform, Serrasalmus maculatus, with asynchronous oocyte development and a prolonged reproductive period. These reproductive strategies result in fish determinate and indeterminate fecundity, respectively. Annual reproductive phases were determined by biometric and histologic analysis of gonads and interpreted according to new proposals for phase classification and stages of oocyte development (with special attention to germinal epithelium activity). Histologically, there were two types of oogonia in the germinal epithelium: single oogonia and those in mitotic proliferation. Oogonial proliferation and their entry into meiosis resulted in formation of cell nests (clusters of cells in the ovarian lamellae). Morphometric analysis was used to estimate germ cell renewal. Based on numbers of single oogonia in the lamellar epithelium, and nests with proliferating oogonia or early prophase oocytes throughout the annual reproductive cycle, oogonial proliferation and entrance into meiosis were more intense during the regenerating phase and developing phase, but decreased sharply (P < 0.05) during the spawning-capable phase. Oogonial proliferation gradually recovered during the regressing phase. We concluded that, independent of species or features of the reproductive cycle, germ cell renewal occurred during the regenerating phase, ensuring availability of eggs for the spawning event.

Oogenesis and reproductive investment of Atlantic herring are functions of not only present but long-ago environmental influences as well

“…As apoptosis also affects follicular cells, apoptosis might actually trigger atresia (47); atresia is seen for both small and large oocytes (48). Evidence shows that oogonial proliferation and folliculogenesis happen shortly after spawning (49). Hence, EOR N of NSSH should be particularly prevalent in MarchApril (Fig.…”

<b>Ovarian histology and fecundity in the evaluation of the reproduction of the invasive species <i>Serrasalmus marginatus</i> (Characidae) on a neotropical floodplain

“…They are developing, spawning capable, regressing and regenerating, according to BrownPeterson et al (2011). These phases are used because they are simpler and in Brazil have been adopted by Wildner et al (2013) for Serrasalmus maculatus, Quagio-Grassiotto et al (2013) for Hoplias malabaricus and Sorubim lima and Agostinho et al (2015) for Hemiodus orthonops.…”

“…The ovarian development phases were attributed according to the macroscopic characteristics proposed by Brown-Peterson, Wyanski, SaboridoRey, Macewicz, and Lowerre-Barbieri (2011), Wildner, Grier, and Quagio-Grassiotto (2013) and Quagio-Grassiotto, Wildner, and Ishiba (2013). A fraction of the left lobe of the ovary was fixed in Bouin solution for at least 48 hours, dehydrated in ethanol, infiltrated using Historesin and shaped into blocks, which were cross-sectioned at a thickness of 5 μm and stained using 0.5% Toluidine Blue, Hematoxilin/Eosin and periodic acid Schiff/ hematoxylin/metanil yellow (Quintero- Hunter, Grier, & Muscato, 1991).…”

“…A fraction of the left lobe of the ovary was fixed in Bouin solution for at least 48 hours, dehydrated in ethanol, infiltrated using Historesin and shaped into blocks, which were cross-sectioned at a thickness of 5 μm and stained using 0.5% Toluidine Blue, Hematoxilin/Eosin and periodic acid Schiff/ hematoxylin/metanil yellow (Quintero- Hunter, Grier, & Muscato, 1991). The germ cells were identified according to Grier, Uribe-Aranzábal, and Patiño (2009) and Wildner et al (2013) and the reproductive phases attributed macroscopically (early developing subphase, developing phase, spawning capable phase, actively spawning subphase, regressing phase and regenerating phase) were validated by the microscopic characteristics of the development stages of more advanced cell types, according to Brown-Peterson et al (2011), QuagioGrassiotto et al (2013 and Wildner et al (2013).…”

Morphology of the urogenital papilla and its component ducts in Astyanax altiparanae Garutti & Britski, 2000 (Characiformes: Characidae)

“…As result fish show considerable anatomical, morphological and physiological differences in their reproductive systems, both in the gonads and in the genital ducts (Lopes et al, 2004;Batlouni et al, 2006;Muñoz et al, 2011). Therefore, examining the reproductive aspects of fish, including sexual dimorphism, fecundity, gonadal morphology and gametogenesis, is important for understanding how species have maximised their reproductive strategies in different environments (Grier & Taylor, 1998;BrownPeterson et al, 2002;Cassel et al, 2013;Siqueira-Silva et al, 2013;Wildner et al, 2013).…”