The structure of the accessory genital mass in Aplysia californica

The accessory genital mass in Aplysia californica is a large hemispherical organ whose main function is to coat the oocytcs and place them in a cordon directly prior to oviposition. The complex pathways through this mass have been reconstructed from serial histological sections. The first diverticulum, second diverticulum and cruciate junction are here described for the first time. The pathways taken by the living oocytes as they pass through the mass and are placed in the cordon are described. Four types of secretory cells are found in the accessory mass: (1) the metachromatic granule cell, (2) the punctate granule cell, (3) the filamentous granule cell and (4) the albumen gland cell.