APPEARANCE OF GIANT EGG MUTANT OF BOMBYX- MORI (LEPIDOPTERA, BOMBYCIDAE) .4. SURFACE-STRUCTURE OF EGGSHELL IN GE EGG

The surface structure of the eggshell of the Giant egg mutant (Ge) of Bombyx mori was observed by a differential intereference contrast micr oscope. Four spatially-differentiated surface regions, called anterior (micropyle region taking form of single flower with many petals), pos terior, dorsal plus ventral, and lateral (unit of network patterns eac h taking shape of regular or irregular polygon which reflects boundary of follicular epithelial cell), were found on the Ge mature eggshell as on the normal eggshell. However, the size of the Ge polygon at the lateral region was smaller than that of the normal eggshell, and the n umber of knobs within the Ge polygon were fewer than in the normal pol ygon. This result suggests that the Ge egg is made by an increased num ber of follicle cells, each of which secretes chorion over a smaller s urface area.