Biosynthesis of agr and beta-Ecdysones from Cholesterol outside the Prothoracic Gland in Bombyx mori.

Labeling experiments have established that cholesterol is converted into alpha-and beta-ecdysones in isolated abdomens of silkworm larvae. Since the isolated abdomens do not contain the prothoracic glands, a doubt is cast on the long-standing principle in insect endocrinology that the prothoracic glands are the source of ecdysone secretion.