Induction of larger eggs by 20-hydroxyecdysone in giant egg mutant phenotypes in the silkworm, Bombyx mori

The influence of exogenous 20-hydroxyecdysone on the giant egg (Ge) mutant of Bombyx mori was investigated. The Ge female pupae injected with the hormone produced larger and heavier eggs than the control Ge pupae injected with water alone, and these characters of the eggs depended upon the dose of the hormone. The area of each polygon, which is observed on the eggshell surface of the enlarged Ge egg, was broader than that of polygon on the control Ge egg, while the total polygon number per whole lateral region remained unchanged. These results indicate that the administration of 20-hydroxyecdysone promoted hypertrophy, without increase in number, of the follicular epithelial cells which undergo choriogenesis. The Ge eggs thus modified would be the largest of the hitherto reported eggs of B. mori.