A hormone from the uterus of the tsetse fly, Glossina morsitans, stimulates parturition and abortion

Unlike most insects, the tsetse female gives birth to a single, fully grown larva at the culmination of each pregnancy cycle, The expulsion of the larva is regulated by a hormone present in rich abundance within the female's uterus, The hormone elicits parturition when injected into neck-ligated females at late stages of pregnancy and abortion when injected at earlier stages, We refer to this highly active material (0.043 uterus equivalents stimulates parturition in 50% of the females) as parturition hormone, Injection of the active extract, which appears to be a peptide or small protein, initiates the series of blood pressure pulsations and uterine contractions normally associated with parturition, The discovery that a uterus extract from the flesh fly also elicits parturition in tsetse suggests that this hormone may be widely distributed in insects. (C) 1997 Elsevier Science Ltd. All rights reserved.