Distribution of APGWa-immunoreactive substances in the central nervous system and reproductive apparatus of Helix aspersa.

The distribution of substances related to the tetrapeptide APGWa was investigated in the central nervous system (CNS) and the reproductive apparatus of Helix aspersa by immunocytochemistry. In the CNS, APGWa immunoreactive neurons were detected in all ganglia except the pedal ganglia. Concerning the mesocerebrum of the cerebral ganglia, only neurons of the right mesocerebral lobe reacted positively to the antiserum. In the genital apparatus, positive neurons fibres were seen in the muscular layer of the penis and, in the gonad, an immunoreactive material occurred on the heads of some spermatozoa. On the basis of these observations and of previous electrophysiological studies, an implication of AGPWa-like peptides in the control of mating behaviour is proposed. The significance of the positive reaction of the spermatozoa remains unclear.