Ultrastructure of the mandibular organ of the shrimp, Penaeus japonicus, in untreated and experimentally manipulated individuals

Abstract

The fine structure of the mandibular organ of the shrimp, Penaeus japonicus, was studied. The cells of mandibular organ contain mitochondria, smooth endoplasmic reticulum and Golgi complex. These organelles do not show any change during molt cycle. Prominent changes were observed in the cells after some steroids or proteinaceous substance. Some changes in the cells also occurred after the eyestalks were ablated. The function of the mandibular organ was considered. Le Roux (1968) described a pair of glandular organs in the cephalothorax of brachyuran decapods. He named them mandibular organs. Since then several studies on the histology and the function of mandibular organs have been published (Aoto et al., 1974, Hinsch and al Hajj, 1975, Byard et al., 1975, Hinsch, 1977, Yudin et al., 1980, Laufer et al., 1984). Nevertheless, the physiological function of the mandibular organ is still unclear. In order to obtain some idea of its function, we performed some experimental procedures with the shrimp, Penaeus japonicus. The results of these experiments are given herein.