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First published online October 10, 2003

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The Journal of Experimental Biology 206, 3913-3921 (2003)
doi: 10.1242/jeb.00625

Sensory innervation of the ovotestis in the snail Helix aspersa

Tomasz Antkowiak and Ronald Chase^*

Department of Biology, McGill University, 1205 Ave Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada

^* Author for correspondence (e-mail: ronald.chase{at}mcgill.ca)

Accepted 22 July 2003

Because oviposition in the land snail Helix aspersa is a metabolically expensive process coupled to a high fixed cost, one expects oviposition to occur only when the clutch size surpasses a minimum value at which the reproductive benefit exceeds the cost. We propose that neural innervation of the gonad allows H. aspersa to monitor oocyte production and ensure an adequate supply of gametes prior to ovulation. The ovotestis is innervated by a branch of the intestinal nerve in which the majority of axon fibres measure <0.2 µm in diameter. We found a strong positive correlation between the number of mature oocytes in the ovotestis and the frequency of spontaneous afferent spikes in the nerve branch. Tactile stimulation of the ovotestis resulted in a 20-fold increase in afferent spikes and an efferent reflex directed towards the ovotestis and the pericardium. Afferent activity also increased 10-fold after an experimentally induced increase in the volume of the ovotestis. These results suggest that the growing oocytes expand the walls of the acini and trigger action potentials in the mechanosensitive nerve terminals that lie within the acinar walls. We hypothesize that the resulting tonic signal is permissive for ovulation. In addition, a phasic sensory signal may occur during ovulation to trigger CNS motor output related to oviposition.

Key words: oviposition, clutch size, oocyte, ovotestis, sensory innervation, land snail, Helix

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				E. GEOFFROY, R. HUTCHESON, and R. CHASE NERVOUS CONTROL OF OVULATION AND EJACULATION IN HELIX ASPERSA J. Mollus. Stud., November 1, 2005; 71(4): 393 - 399. [Abstract] [Full Text] [PDF]

				K. Phillips EGG COUNTING SNAILS J. Exp. Biol., November 15, 2003; 206(22): 3888 - 3888. [Full Text] [PDF]