Morphological analysis of oocyte development of piracanjuba Brycon orbignyanus during the reproductive cycle

Abstract

In the present work the oogenesis of Brycon orbignyanus (Valenciennes, 1849) during the reproductive cycle was studied. Adult females were randomly caught at each two months. Fragments of the ovaries were processed for light microscopy. During the whole reproductive cycle, six types of oocyte were observed: chromatin-nucleolus (phase I), perinucleolar (II), alveolus-cortical (III), vitellogenic (IV), post-vitelogenic (V) and atresic (VI). The morphological changes detected in the ovaries occurred in a cyclic way, and can be described in four stages of development of the gonad: Rest, Initial Maturation, Maturation and Regression. Between December and January (end of spring and beginning of summer) occurs the maturation process.