Ultrastructural alterations induced by fenitrothion on fat body cells and midgut cells of Tenebrio molitor L. (Insecta, Coleoptera) larvae ZBIGNIEW ADAMSKI1,2*, MONIKA BANASZKIEWICZ2 and KAZIMIERZ ZIEMNICKI2  1 Electron and Confocal Microscope Laboratory and 2 Department of Animal Physiology and Developmental Biology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, PoznanΪ, Poland Abstract Exposure of Tenebrio molitor larvae to the insecticide fenitrothion affected their growth, moulting and survival and caused alterations in the ultrastructure of the fat body cells and midgut cells. The insecticidal stress altered the appearance of the biological membranes. Even though the mortality was low, the nuclei, ground plasm, endoplasmic reticulum and mitochondria revealed numerous prominent malformations: invaginations and swelling of the nuclear envelope, high ratio of condensed chromatin, swollen endoplasmic reticulum elements, heterogeneous fatty acid storing vesicles and fewer cristae in the mitochondria of the fat body cells.   < back .