Reproductive Cycle, Ovarian Development, and Vertebrate-Type Steroids Profile in the Freshwater Prawn Macrobrachium Rosenbergii

Abstract

Abstract This study is intended to characterize the ovarian development and hemolymph vertebrate-type steroids concentration during the reproductive cycle of the freshwater prawn, Macrobrachium rosenbergii. A five-stage classification based on the external observation of the ovary's size and color as seen through the tegument was used. The results showed the existence of a direct correspondence between the ovarian stages and the gonadosomatic index, the oocyte diameter, and the characteristics of ovarian histology. In each stage total bleeding of the prawns was conducted and the hemolymph concentrations of 17β-estradiol (E2), testosterone (T) and 17α-hydroxyprogesterone (17-OHP; conjugated and unconjugated) were determined by solid-phase radioimmunoassay (RIA). High levels of unconjugated 17-OHP, relatively constant concentrations of unconjugated T, and null concentration of unconjugated E2 were found throughout the five stages considered. Nonetheless, low levels of E2 were determined in all stages, in co...