Abstract
The developing embryos of the saturniid silkmoth, Samia cynthia ricini, contain eclosion hormone, which can elicit precocious adult eclosion in Bombyx mori. In this study its activity first become detectable in embryos at the middle stage of embryogenesis. Thereafter hormonal activity sharply increased with age and reached a maximum level (0.23 units/ embryo)just after hatching. Eclosion hormone activity was detected in both the head and thorax-abdomen of embryos. The proportion of the eclosion hormone increase in the head region of the ligated animal was higher than that of the abdominal segment. Eclosion hormone was partially purified 290-fold from Samia embryos. Molecular weight of the embryonic eclosion hormone was about 8, 500±1, 000 daltons as judged by gel-filtration on a Sephadex G-50 (superfine). Eclosion hormone is considered to be involved in hatching induction in Samia cynthia ricini.
