Stimulation of egg-laying by nerve extracts in slugs

Abstract

LITTLE is known about the mechanism of egg-laying in mollusca, although their reproduction is under endocrine control. In the freshwater snail Lymnaea stagnalis, cauterisation of the neurosecretory caudodorsal cells of the cerebral ganglia causes cessation of oviposition. Subsequent injection of a homogenate of cerebral commissures induces oviposition in all snails with caudodorsal cells. This suggests that the caudodorsal cells produce a hormone, which stimulates oviposition¹. Kupfermann² induced ovulation and oviposition in Aplysia californica by injection of a homogenate of neurosecretory cells, the so-called bag cells, from the abdominal ganglion of this species. Although the morphology of the reproductive system has been studied in various terrestrial slugs^3–7, there are conflicting reports about the control of reproduction. I report here that homogenates of the central ganglia and tentacles, which are the sites of neurosecretory cells^8,9, stimulate egg-laying in the slugs, Deroceras reticulatus (=Agriolimax reticulatus) and Limax flavus.