摘要:The aim of this study was to determine the effects of Polyaromatic Hydrocarbons (PAHs) on the fine structure of the hepatopancreas of Palaemon serratus . For this purpose, shrimps were intramuscularly injected with sublethal dose (100 ng μL-1) of perylene, christen and benzo (a) pyrene. Samples of hepatopancreas were then taken for electron microscopic examinations (three weeks postinjection). Ultrathin sections revealed that the exposure changed the structure of hepatopancreatic epithelial cells (R- and F-cells) in perylene and christen injected specimens. However, benzo (a) pyrene treated group was less affected. Major changes observed in the hepatopancreatic cells included thickening and folding of basal lamina, distorted microvillous border, condensation and margination of heterochromatin, dilation and fragmentation of RER, well-developed lysosomal compartment and swelling mitochondria. Such ultrastructural changes could serve as a useful research tool and a general biomarker in studies of toxic stress in aquatic habitat.