Ovarian differentiation and development in cachara Pseudoplatystoma fasciatum

Abstract

One thousand five hundred cachara or tiger shovelnose catfish Pseudoplatystoma fasciatum, obtained from induced reproduction, were used to determine the onset of ovarian differentiation and development and to record the main characteristics of this process. Samples were collected from 0 to 240 days post-fertilization (dpf) and the results classified into stages I-XII. Ovarian formation was histologically detected for the first time when juveniles measured mean ± s.d. 51·5 ± 8·3 mm total length (LT ) at 39-45 dpf (stages I-V), with intense somatic cell proliferation originating in the ovarian cavity. Both LT and age of fish had a positive correlation (P < 0·001) with ovarian differentiation, but LT showed a greater correlation (r(2) = 0·95) than age (r(2) = 0·85), especially during the initial stages of development. From stages VI to VII, the ovarian cavity was enlarged and undifferentiated oogonia were present. At stage VIII, small projections formed in the ovarian stroma towards the ventral region of the gonad (future ovarian lamellae) and the basal membrane and differentiated oogonia nests could be seen. At stages IX and X, the germ cells entered meiosis and folliculogenesis was completed by stages XI and XII, which can be considered late in comparison to other Siluriformes. This study has demonstrated that ovarian differentiation in P. fasciatum begins with an intense proliferation of squamous epithelial cells (somatic cells) during the early stages of development and that sex inversion protocols could, thus, be applied successfully before this period. Furthermore, the results have demonstrated that both size and age can influence gonad differentiation and development in this species.

Piaractus mesopotamicus gonad differentiation

“…Moreover, with the management conditions applied in this study, we observed a relatively late gonadal differentiation process in pacu (♀: 150 days, 18.21 ± 1.22 g and mean length of 9.55 ± 0.65 cm) compared with other tropical species used in aquaculture, such as cachara, Pseudoplatystoma fasciatum (♀ and ♂: 39–45 days; 51.5 cm and 0.66 g) (Valentin et al, 2016), lambari, Astyanax altiparanae , (♀: 58 days and ♂: 73 days) (Adolfi et al, 2015) and tambaqui, Colossoma macropomum (♀ 4.0 cm) (Lobo et al, 2020). In this concern, we must also consider that the growth rates obtained in the present study were far below the growth rates reported for other pacu growth‐out phase studies.…”

“…compared with other tropical species used in aquaculture, such as cachara, Pseudoplatystoma fasciatum (♀ and ♂: 39-45 days; 51.5 cm and 0.66 g) (Valentin et al, 2016), lambari, Astyanax altiparanae, (♀:…”

Testicular differentiation and development in South American catfish, surubim, Pseudoplatystoma fasciatum

“…Early identification of the testis was possible due to the future fringes appearance of the gonad as a result of the proliferation of the stroma and also the early cellular arrangement (circular formation) of somatic cells in the distal region; which later originated the sperm ducts in P. fasciatum and which has been reported in several gonochoristic species (Kobayashi et al, 2011;Komatsu, Nakamura, & Nakamura, 2006;Meijide, Lo Nostro, & Guerrero, 2005). Therefore, the morphological indications of gonadal differentiation may be related to the different arrangements of somatic and germ cells during early development (Mazzoni, Grier, & Quagio-Grassiotto, 2010, 2014Valentin et al, 2016), and may precede the formation of sperm ducts in males and the start of meiosis in females (Kobayashi et al, 2011;.…”

“…It alters gonad morphology and affects growth rate and maturation age (Strussmann, Cota, Cota, Phonlor, Higuchi, & Takashima, 1996;Strussmann, Takashima, Takashima, & Toda, 1996); which are characteristics of commercial interest, especially in monosex farming (Marjani, Jamili, & Mostafavi, 2009). Therefore, the morphological indications of gonadal differentiation may be related to the different arrangements of somatic and germ cells during early development (Mazzoni, Grier, & Quagio-Grassiotto, 2010, 2014Valentin et al, 2016), and may precede the formation of sperm ducts in males and the start of meiosis in females (Kobayashi et al, 2011;. Early identification of the testis was possible due to the future fringes appearance of the gonad as a result of the proliferation of the stroma and also the early cellular arrangement (circular formation) of somatic cells in the distal region; which later originated the sperm ducts in P. fasciatum and which has been reported in several gonochoristic species (Kobayashi et al, 2011;Komatsu, Nakamura, & Nakamura, 2006;Meijide, Lo Nostro, & Guerrero, 2005).…”

Gonadal sex differentiation in hybrid snakehead of Channa argus (♂) × Channa maculate (♀)

“…The determination of gonadal sex differentiation is important for the artificial sex reversal induction (Valentin et al., ; Zhao et al., ). Sex reversal in most teleost fish is induced during or before the period of gonadal sex differentiation, which is plastic in fish and thought to be controlled by genetic and environmental factors (Lou et al., ; Nakamura, Kobayashi, Chang & Nagahama, ).…”