On the neuroendocrine control of ovarian development in the Monarch butterfly

Abstract

Abstract Several methods have been used to examine the role of the neuroendocrine system in the regulation of ovarian development in the Monarch butterfly, Danaus plexippus . Ovarian development ceases after neck ligature, removal of the retrocerebral complex, disconnection of the retrocerebral complex from the brain, and after removal of the neurosecretory cells and associated neurons of the medial pars intercerebralis. Removal of the retrocerebral complex causes oocyte resorption in mature females. Normal ovarian development was obtained by injecting material with high juvenile hormone activity into animals lacking the retrocerebral complex, but normal ovarian development was not obtained in neck‐ligatured animals injected with the same material. The results suggest that the brain and corpora allata both act to regulate ovarian growth in this species. The brain apparently stimulates posteclosion corpora allata activity. The medial neurosecretory cells of the pars intercerebralis, or some other cephalic center, may produce a hormone requisite for quantitatively normal öogenesis. The corpora allata apparently stimulate vitellogenin synthesis.