Abstract
To make clear the ultrastructural differences between both larval and pupal cuticular formation in Bombyx mori, these integuments during the larval and the larval-pupal molts were studied by transmission electron microscope. In larval molt microvillus and pore canal arised from the epidermal cell is active for nodule and wrinkle formation during the epicuticular formation, and the epicuticular surface are undulated by these projections. During the larval and larval-pupal molt, the epicuticular surface is comparatively smooth, and the microvilli are conspicuous but not the pore canals. The cuticular humps are formed on the boundary between two epidermal cells, and these correspond for the frame of polygons of the cuticular surface. It is considered that these differences mentioned are based on the differences of the growth after both cuticular for mations.
