Observation of the embryonic development in Pseudoplatystoma coruscans (Siluriformes: Pimelodidae) under light and scanning electron microscopy

Abstract

SummaryPseudoplatystoma coruscans is a very popular species for tropical fish culture as it has boneless meat of delicate taste and firm texture. Few studies on fish reproductive biology refer to the morphological features of eggs. The goal, therefore, of this present work was to perform a structural and ultrastructural analysis of fertilization and embryonic development in P. coruscans. The incubation period, from fertilization to hatching, lasts 13 h at 28/29• C and 18 h at 27• C. The oocytes had a mean diameter of 0.95 mm and hatched larvae were 2.55 mm in diameter. Analysing their development, we observed round, yellow oocytes that bore a double chorion membrane and a single micropyle. At 10 s after fertilization, several spermatozoa were detected attached to the oocyte surface. After 1 min of development, a fertilization cone that obstructed the micropyle could be observed. Segmentation started between 20 and 30 min after fertilization, when the egg cell was then formed. The first cleavage occurred between 30 and 45 min after fertilization, prior to reaching the morula stage (75 and 90 min after fertilization). The epiboly movement started at 120 and 180 min after fertilization and ended at 360 and 480 min after fertilization. Differentiation between cephalic and caudal region was detected after 420 and 600 min after fertilization and larvae hatched between 780 and 1080 min after fertilization. Seven main embryonic development stages were identified: egg cell, cleavage, morula, blastula, gastrula, segmentation with differentiation between cephalic and caudal regions, and hatching.

Brycon gouldingi(Teleostei, Characidae): aspects of the embryonic development in a new fish species with aquaculture potential

“…In B. gouldingi, the anterior region of the neural tube was expanded, giving rise to anterior brain (prosencephalon), medium brain (mesencephalon) and posterior brain (rhombencephalon) as described in D. rerio by Kimmel et al (1995), G. morhua by Hall et al (2004), P. lineatus by Ninhaus-Silveira et al (2006) and by Marques et al (2008) in P. corruscans.…”

Structural analysis of fertilization in the fish Brycon orbignyanus

“…However, fertilization studies in Brazilian fish species have received little attention so far. Reports on fertilization events are available for Prochilodus lineatus, used as an experimental model (Freire-Brasil et al, 2002) and, subsequently, other studies have been carried out in some native species at the Aquaculture Center -UNESP, as follows: Salminus brasiliensis (Nakaghi et al, 2006), Pseudoplatystoma coruscans × P. fasciatum hybrids (Faustino et al, 2007), P. coruscans (Marques et al, 2008), Paulicea luetkeni and Brycon amazonicus (Nakaghi, unpublished data). Studies that involve native fish species are essential to provide both a better knowledge about their biology and reproductive features and a proper management in fish culture systems.…”

Desarrollo Embrionario del Capaz Pimelodus grosskopfii (Steindachner, 1879)

“…Estos rangos amplios de duración del desarrollo embrionario que se observan para una misma especie, producen un crecimiento asincrónico de las larvas y por lo tanto heterogeneidad en su tamaño, lo cual favorece el canibalismo entre ellas (Kestemont et al, 2003). La doble membrana ha sido poco estudiada y su función específica aún no ha sido definida, pudiendo ser considerada una característica propia de las especies del orden Siluriformes (Marques et al, 2008). Por otro lado, la presencia de un amplio espacio perivitelino observado en esta especie tiene relación con la incorporación de agua por el óvulo durante la maduración meiótica, fenómeno denominado hidratación llegando a alcanzar el contenido de agua en el huevo y en los embriones tempranos hasta el 95 % de su peso (Cerdà, 2002).…”

“…El patrón de segmentación observado en capaz (P. grosskopfii) es de tipo meroblástico; la blastomeración observada para la especie es análoga a la reportada para algunos silúridos como Rhamdia quelen, Pseudoplatystoma corruscans, Leiarius marmoratus (Pereira et al, 2006;Marques et al;Zapata-Berruecos et al, 2008) y para otras especies del grupo de los carácidos como Brycon amazonicus y Brycon sinuensis (Clavijo-Ayala & Arias-Castellanos, 2004b;Atencio-García et al, 2006).…”