Dynamics of testicular maturation during the reproductive cycle of Salminus hilarii (Teleostei, Characidae) in a natural habitat.

Abstract

The objective was to describe the morphophysiological changes of Salminus hilarii testis during the annual reproductive cycle. The animals were collected in the Alto Tietê River Basin between Salesópolis and Biritiba Mirim cities (SP). Macro/microscopic analyzes of the testes allowed the classification of three stages (prespermatogenic, spermatogenic and regression) and six cell types (spermatogonia, spermatocytes, spermatids, spermatozoa, Sertoli and Leydig cells). The plasma concentration of estrogen/progestogen did not change during the reproductive cycle. However, androgens, testosterone and 11-ketotestosterone increased progressively with testicular maturation (continuous germ-to-discontinuous epithelial changes) and concomitantly with increased gonadosomatic index. These morphophysiological results suggest that the reproductive period occurs between the months of September to February.