Structural and ultrastructural analysis of the embryonic development of the siluriform Rhamdia quelen (Quoy & Gaimard, 1824)

Abstract

The species Rhamdia quelen is a fish from the siluriformes order, Heptapteridae family, widely distributed throughout South America, with great ecological and aquaculture importance. Its reproductive period is from August to March. It is a rheophilic species, with its natural stocks affected by the construction of dams and dams. Thus, this study aims to analyze and describe morpho-temporally all the structural changes that occurred during the embryogenesis of R. quelen, at the structural and ultra-structural level, contributing to the expansion of knowledge about the reproductive biology of the species, assisting in studies on the preservation of the species, such as for breeding in captivity. For this experiment, embryos will be obtained from adult and mature breeders, belonging to the Aquaculture Sector, at UNESP, Botucatu Campus. After fertilization of the oocytes, the eggs will be placed in vertical incubators. Collections will be carried out from the moment of fertilization every 15 minutes in the first 2 hours of embryogenesis, then every hour until the larvae hatch. R. quelen embryos will be fixed in a 2.5% glutaraldehyde solution in 0.1M sodium phosphate buffer, pH 7.3. To study their initial ontogenetic structure, samples of fixed embryos will be selected at each embryonic stage, embedded in historesin, subjected to microtomy, stained and analyzed under light microscopy. For analysis under scanning electron microscopy, they will be post-fixed in 0.5% osmium tetroxide, dehydrated in ethanol, dried in a critical point device, and covered with gold film in a metalizer. The results of this work will be organized in the form of a work for the completion of the student's undergraduate course, and published in the form of a scientific article in an indexed, high-impact journal to disseminate the knowledge obtained.