Ovarian Prothoracicotropic Hormone Activity in the Silkworm, Bombyx mori : Lepidoptera : Bombycidae

Abstract

Prothoracicotropic hormone (PTTH) activity assayed in brainless pupae of Samia cynthia ricini is present in the mature eggs of the silkworm, Bombyx mori. Comparable activity was also found in eggs which had matured in brainless moths and in isolated abdomens. No significant differences in chemical components were shown in the eggs developed at three different hormonal milieus. It is possible to conclude that the ovarian PTTH is synthesized during egg maturation.