REPRODUCTIVE-CYCLE OF OVARIAN DEVELOPMENT AND VITELLOGENIN PROFILES IN THE FRESH-WATER PRAWNS, MACROBRACHIUM-ROSENBERGII

The objectives were to characterize the ovarian development and hemolymph vitellogenin concentrations during the reproductive cycle in the freshwater prawn, Macrobrachium rosenbergii. The ovaries of M. rosenbergii were classified into five developmental stages, and the ovarian histology of each stage was characterized. The ovarian stages correlated closely with the gonadosomatic index, the oocyte diameters, and the characteristics of ovarian histology. Sequential bleeding at 3-day intervals from each of seven prawns was also conducted for at least two reproductive cycles. Vitellogenin concentrations in the hemolymph were measured with a validated enzyme-linked immunosorbent assay. Vitellogenin concentrations in the hemolymph showed similar profiles in the 18 reproductive cycles tested in these prawns. Vitellogenin concentrations increased in the hemolymph of prawns in the early stages of ovarian development (stage I or II) and were maintained at high levels until stage V. Hemolymph vitellogenin concentrations fell abruptly during (or just prior to) oviposition and remained at low levels until the embryos hatched or were removed. There was not a close correlation between ovarian stages and the concentrations of circulating vitellogenin.