Neurosecretion and Molting in Some Parasitic Nematodes

The adult female of Ascaris lumbricoides possesses a numberof nerve cells containing material which stains with paraldehyde-fuchsin.Among others, most of the primary sensory cells in the lipsare fuchsinophilic. Ascaris does not survive outside its host,so that it is impossible to ascribe a function to these cells. Phocanema decipiens possesses similar cells in the dorsal andventral ganglia which exhibit a cycle of secretion correlatedwith the burst of cytological activity which accompanies thedeposition of the new cuticle. Ligation experiments have demonstratedthat a new cuticle can be deposited in the absence of theseneurosecretory cells. Our most recent experiments suggest thatthe neurosecretory cells may control the release of leucineaminopeptidase in the excretory gland, a substance which isthought to be responsible for ecdysis.