Cytochemical studies on the PAS-positive and metachromatic substances in the cells of enteric epithelium of Achoea janata (Noctuidae: Lepidoptera).

Of the different polysaccharides present in the cells of insects the PAS-positive and metachromatic substances were studied in the cells of the enteric epithelium of the moth Achoea janata during its larval period and following metamorphosis. The amounts of both the substances progressively decrease in sequential pupal stages. The reaction intensity at the cell apex is higher than at the cell periphery. Reduction in the amount of carbohydrate material in the epithelial cells of the mid-gut is associated with change in intracellular localization (by vanishing from definite sites, not by migration). The loss of metachromatic substances is, however, more rapid than that of PAS-positive ones in the cells of the same region. It appears likely that there are simultaneous conversions of both kinds of substances into chitin precursors, independent of each other. No movement of these substances for the chemical change to be accomplished at specific sites in the cell is found. Association of PAS-positive substances with the formation of peritrophic membrane has been discussed.