The Rhodnius testis: hormonal effects on germ cell division

Abstract

The spermatogonial cells of the Rhodnius testis exhibit a basal level of division activity in the absence of morphogenetic hormones. Ecdysone, naturally induced by feeding or injected in physiological doses, approximately doubles the mitotic index as measured by colchicine-metaphase accumulation. Juvenile hormone production in the molting larvae or application of juvenile hormone mimic farnesyl methyl ether abolishes the ecdysone-stimulated increase in mitotic index, but has no effect on the basal level. Similar results are obtained in fed and unfed decapitates, and in surgically manipulated insects. In contrast, natural induction of ecdysone secretion is shown to be ineffective in altering the duration of the meiotic prophase.