Ovarian maturation of wild Farfantepenaeus paulensis in relation to histological and visual changes

摘要

The present study describes the ovarian development stages of wild Farfantepenaeus paulensis (Perez-Farfante) through the combined observation of histological and visual characteristics. Twenty-five females (61.8 +/- 2.4 g) were captured in 35-40-m deep waters off southern Brazil (27degreesS). The females were grouped according to the size and shape of their ovary and then killed. The colour of the fresh ovary was compared with a chromatic scale catalogue. Analysis of the histological sections of each ovary determined the morphological characteristics, size and frequency of the different oocyte types. Based on these characteristics, four distinct stages of ovarian maturation are proposed: stage I (immature), characterized by the presence of small basophilic oocytes (52.1 +/- 19.9 mum) and ovary colour ranging from translucent to creamy: stage II (developing), with yolky oocytes (YOs) (144.2+/-26.1 mum) and a light green colour; stage III (mature), presenting large YOs but with cortical rods (235.0 +/- 30.2 mum) and an olive-brown colour; and stage IV (spent), with atretic oocytes and the same ovary colour pattern as stage I. The gonadosomatic index ranged from 1.6 (stage IV) to 13.7% (stage III) and was closely related to the different ovarian maturation stages. The observation of visual features coupled with histological characteristics was found to represent a reliable procedure to evaluate the ovarian maturation of E paulensis.