Molting in a parasitic nematode, Phocanema decipiens. IV. Ecdysis and its control

The last ecdysis of Phocanema in in vitro culture is described briefly. Ecdysis is accompanied by the synthesis in the excretory gland of the enzyme leucine aminopeptidase and its release via the excretory duct into the space between the two cuticles. A previously described cycle of neuro-secretion is also correlated with these events. Extracts of the anterior ends of worms with active neurosecretory cells stimulate the synthesis of leucine aminopeptidase in isolated excretory glands. Rearing the worms in a non-nutrient medium abolishes the neurosecretory cycle and hence the synthesis of leucine aminopeptidase, and the worms fail to undergo ecdysis. The excretory system of Phocanema is described, and histochemical evidence presented for protein synthesis in the gland during ecdysis.