Structural analysis of the embryonic development inBrycon cephalus(Günther, 1869)

Abstract

SummaryThe embryogenesis of Brycon cephalus was established in seven stages: zygote, cleavage, blastula, gastrula, segmentation, larval and hatching, in an incubation period of 11 h (26 • C). The zygote phase was observed directly after fertilization and egg hydration. Cleavage began at 0.5 h of incubation and extended up to the morula phase (1.5 h; +100 blastomeres). Cleavage was meroblastic and underwent the following division pattern: the first five divisions were vertical and perpendicular to each other, following the model 2 × 2, 4 × 2, 4 × 4 and 4 × 8. The sixth division was horizontal and occurred at 1.25 h after fertilization, giving rise to two cell layers (4 × 8 × 2) with 64 blastomeres. At the blastula stage (1.25-1.5 h), an irregular space between the blastomeres, the blastocoele, could be detected and the periblast structure initiated. The gastrula (1.75-6.0 h) was characterized by the morphogenetic movements of epiboly, convergence and cell involution, and formation of the embryonic axis. The segmentation stage (7-9 h) comprised the development of somites, the notochord, optic, otic and Kupffer's vesicles, neural tube, primitive intestine and ended with the release of the tail. The larval stage (up to 10 h) was characterized by the presence of 30 somites and growth and elongation of the larvae. At the hatching stage, the embryos presented more than 30 somites and exhibited swimming movements and a soft chorion. The blastomeres presented euchromatic nuclei, indicating a high mitotic activity and many yolk globules in the cytoplasm. The periblast was constituted of a layer with several nuclei and many vesicles, which grew during the epiboly movement.

Comparative Analysis of the Oocytes and Early Development of Two Species of Curimatidae Teleost Fish

“…The micropyle is a small opening in the zona radiata, composed of the vestibule and micropylar channel that reaches the oocyte's plasmatic membrane and participates in the fertilization process (Ganeco and Nakaghi, ). In this study, oocytes of both species showed a funnel‐shaped micropyle, a common pattern similar to other Characiformes species (Ganeco et al., ; Alexandre et al., ; Isaú et al., ).…”

Induced spawning and early ontogeny in hatchery-reared catfish Zungaro jahu (Siluriformes: Pimelodidae)

“…In jahu, the blastomeres become smaller as their number increase (Marques, 2008), a condition which is also observed in other teleosts: Prochilodus lineatus (NinhausSilveira et al, 2006), Brycon cephalus (Alexandre et al, 2009).…”

Embryonic development and larval growth of Brycon nattereri Günther, 1864 (Characidae) and its implications for captive rearing

“…Brycon nattereri embryogenesis can be considered as long compared with other species of the genus Brycon, such as B. cf. erythropterus (Eckmann, 1984), B. orbignyanus (Nakatani et al, 2001), B. insignis (Andrade-Talmelli et al, 2001;Isaú et al, 2013), B. siebenthalae (Clavijo-Ayala & Arias-Castellanos, 2004), B. orthotaenia (Gomes et al, 2013) and B. cephalus (Alexandre et al, 2010) in which embryonic development was concluded between 11 and 30 h after fertilization, at 23 to 28°C (Table 3). Temperature is the main factor controlling the development rate of fish (Kamler, 1992).…”