Organogenesis of Genital Organs and Androgenic Gland in the Kuruma Prawn

Abstract

For the kuruma prawn Penaeus japonicus, histological studies were conducted to reveal the time schedule of organogenesis of the genital organ and the androgenic gland during postlarval periods from the 20th day-stage (P20) to P110.
The gonad, the vas deferens, and the ejaculatory bulb have already been observed at P20. The gonad had primordial and mesodermal cells in its cords situated on the dorsal midgut gland. The proximal vas deferens of P30 was located near the descending aorta. The distal vas deferens consisted of fibrillar connective tissue provided with a longitudinal recess. The ejaculatory bulb was composed of epithelial cells and fibrillar connective tissue linked to the network of loose con-nective tissue under the epidermis of the coxopodite. The petasma was found at P50. At P55, the androgenic gland was recognized as an organ of cellular mass at the posterior surface of the ejaculatory bulb wall. Until P60, sex discrimination of the gonad was difficult.