Effects of ecdysone and juvenile hormone on epidermal cell development in Hyalophora cecropia

Pupae of Hyalophora cecropia were injected with various doses of beta-ecdysone (molting hormone) or juvenile hormone and the epidermal cell ultrastructure was then studied with the electron microscope. The hormonal effects were rapidly manifested and appeared to be cell specific and dose dependent. The initial response to both hormones was an outward blebbing of the apical plasma membrane. Large doses of beta-ecdysone elicited both precocious cuticle deposition and premature autophagic vacuole formation. Juvenile hormone prevented the appearance of the autophagic vacuoles which normally preceded cell differentation into cells capable of adult synthesis. After prolonged exposure to juvenile hormone, there appeared to be an exaggerated separation of the epidermal cells at the basal region suggesting that the juvenile hormone may act at the membrane level.