Structure of antennal gland in kuruma prawn Penaeus japonicus

A gross anatomy of the antennal gland was conducted for the prawn Penaeus japonicus. Using the histological slices of the second antenna, contour lines of the antennal gland were traced to reconstruct its clay model. The opening site of the organ was observed with a scanning electron microscope to obtain information about urine excretion. The antennal gland was composed of a coelomosac, labyrinth and urinary bladder. The coelomosac as well as the urinary bladder showed a complex of highly diverged vesicles. It had basically a median, transversal and lateral sacs. Some of these components spread to the thoracic region. The labyrinth was located in the median coelomosac. The transversal coelomosac con-nected the two glands behind the brain. The urinary bladder was situated distal to the labyrinth, leading to an opening slit on a small disc which was formed as a cuticular protrusion at the inside coxopodite of the second antenna. Urine excretion seemed to occur due to hemolymph pressure or inner pressure of the coelomosac.