Proctolin-immunoreactive neurons persist during metamorphosis of an insect: A developmental study of the ventral nerve cord of Tenebrio molitor(Coleoptera)

Summary Proctolin-immunoreactive neurons in all neuromers of the ventral nerve cord of Tenebrio molitor L. have been quantitatively demonstrated and mapped throughout metamorphosis. Each neuromer contains an anterior and a posterior group of neurons with light and dark staining properties as revealed by peroxidase-antiperoxidase labeling. Serial homologous subsets of dark staining neurons with central and peripheral projections have been identified and found to persist during morphogenetic changes from the larva to the adult. Most neurons maintain their topological and structural characteristics throughout metamorphosis. The identified proctolin-immunoreactive neurons exhibit structures similar to those described in other insect species; some may correspond known motoneurons.