Maintenance of the Prothoracic Gland by the Juvenile Hormone in Insects

Abstract

THE corpora allata, two small glands connected to the insect's brain, secrete the juvenile hormone which is responsible for larval syntheses and is thus a deterrent to adult differentiation. Larval–larval moults occur in the presence of a high titre of juvenile hormone, the larval–pupal moult in the presence of a decreased titre of juvenile hormone, and the moult from pupa to adult in the absence of juvenile hormone. Other physiological processes in some insects which appear to be governed by a secretion(s) from the corpora allata which may or may not be identical with the juvenile hormone are egg maturation and the secretory function of accessory sex glands¹, maintenance of pupal diapause², maintenance of larval diapause^3,4, mating⁵, and perhaps the overall metabolism of the insect⁶. Whether the corpora allata secrete one, two or several hormones is still an open question which will not be definitely answered until chemical purification of all these principles is completed.