Histological and morphological study of the embrionary development of the capitan de la sabana (Eremophilus mutisii)

Abstract

Eremophilus mutisii, due to its vulnerable condition and its potential for fish farming, generates research challenges; one of them is to know the embryonic changes of the E. mutisiibased on morphological and histological features from fer-tilization to hatching. The embryos were obtained from adult and sexually mature individuals of the Capitan de la Sabana (Eremophilus mutisii), sexually induced with carp pituitary extract. Oocytes and semen were obtained by abdominal pressure 24 hours after the last dose at 14±1°C. Sampling was performed every 60 minutes for the first twelve hours post-fertilization (HPF); from here on at hatching, the sam-ples were fixed every 6 hours. The embryos were fixed in 4% formalin for observing the morphological features and for the histological studies. Results revealed that the fertilized eggs had spherical shape, light green color and average diameter of 1270μm. The first cleavage at 2 HPF was observed, the blastulation began at 9 HPF. Epibolic movements and gastru-lation were observed from 12 HPF to 30 HPF with blastopore closure. At 60 HPF the yolk sac tail detachment was evident and at 66 HPF the first autonomous movements began. Finally, at 72 HPF, the hatching began, showing absence of pigmentation and evidencing a rudimentary digestive tract without oral and anal opening. It was observed the presence of abundant yolk sac with continuous vertical movements of the larva.