Macroscopic and microscopic studies of annual ovarian maturation cycle of Shirbot Barbus grypus in Karoon river of Iran

Abstract

The aim of this investigation was to study macroscopic and microscopic structures of ovaries in Barbus grypus of Karoon river and their changes during annual maturation cycle. For this purpose, 120 adult B.grypus with a mean weight of 835.0 to 1012.0 g, were caught from Karoon river and transferred alive to the laboratory. After biometrical studies, the weights and morphological appearances of gonads were recorded. Then, tissue samples from the anterior, middle and posterior portions of the gonad were excised and fixed in Bouin's solution. For microscopical studies, 5 μm paraffin sections were prepared and stained with haematoxylin and eosin and periodic acid Schiff (PAS). Gonado-somatic indices, macroscopical and microscopical changes of ovaries were studied during different months of the year. The results showed that gonado-somatic index ranged from 0.35 ± 0.080% in September to 2.25 ± 0.321% in June, and the maximum values were seen in June. Cyclic changes of ovarian maturation were divided into seven stages histologically. Ovarian maturation cycle in B. grypus began in late summer. Spawning period of B. grypus continued approximately from late April to early August, which indicated that B. grypus has a prolonged spawning season. Ovarian type of B. grypus was group synchronous with a capacity for multiple ovulations within a reproductive season.