Monoamine-containing varicosities in the neural sheath of a gastropod mollusc demonstrated by glyoxylic acid histofluorescence.

The glyoxylic acid monoamine-detecting technique of Bolstad et al. (1979) was applied to wholemounts of intact ganglia of the gastropod mollusc Philine aperta. A dense network of fluorescent varicosities was found in the sheath of the suboesophageal, visceral and genital ganglia, and most of their nerves. Drug treatment experiments suggest that these projections to the neural sheath contain serotonin. The significance of these terminals in the sheath is discussed and proposals for further work are given.