Follicular atresia in ovaries of Prochilodus lineatus

During the reproductive period, primary follicles are formed cyclically in the ovary of teleost, which mature and are released at the ovulation time. However, some of them develop a process of atresia with degeneration and resorption, which to be considered a physiological event should prevail at the end of the reproductive cycle. Morphological characteristics of ovaries of Prochilodus lineatus were analyzed for the presence of atresic follicles as indicators of possible changes in their reproductive biology affecting the repopulation of the species. In the ovaries of P. lineatus dominated the morphological changes that correspond to the so-called type I atresia, and atresic follicles were observed in fish with low gonadosomatic index who were at the end of the reproductive cycle. Detected follicular atresia could not be linked to a pathological process that causes a decline of the species in the Parana river ecosystem.