Histology of the hepatopancreas of the freshwater prawn Palaemonetes argentinus (Crustacea, Caridea)

The aim of this study is to describe the histological structure of the hepa topancreas of P. argentinus in intermoult stage in order to provide a basel ine for future analysis of its modifications as indicator of environmental stress. Adults at sexual rest of both sexes were collected from Sotelo stre am, tributary of Mar Chiquita lagoon, Argentina (38 degreesS 55 degreesW). P. argentinus hepatopancreas was studied by using histological techniques. The hepatopancreas is a bilaterally bilobed brown-yellowish organ. The stru cture is formed by a mass of blind tubules, with scarce intertubular space. Each tubule consists of a cylindrical epithelial layer surrounded by a bas al lamina and myoepithelial cells. Four cellular types were recognized whic h represent E (embryonic), F (fibrillar), R (resorptive) and B (blisterlike ) cells of other decapods. E-cells were found in mitosis and some F-cells h ad signs of cellular death. B-cells were observed in different phases of ho locrine secretion and some groups of desquamated cells appeared at medial a nd proximal zones, revealing an important cellular turnover rate. According to these observations F, R and B cells are differentiated independently fr om E-cells.