Organization of sensory pathways in the anterior tentacle of Helix pomatia L. A light microscopic study

Morphology of the sensory cells in the anterior tentacle and their connection with the tentacular ganglion as well as the organization of the tentacular ganglion have been investigated using double chromation method. Only one kind of sensory neurone, the primary receptor cells could be found in the sensory cup of the anterior tentacle and they were found to be arranged in columnar form. Between the sensory cells a few unipolar neurons having only dendritic process also could be found. The axonal processes of the bipolar receptor cells form the fascicles of the sensory axons which enter the peduncles of the tentacular ganglion. Inside the peduncles, two different parts could be distinguished namely one consisting of bundles of fibres and other consisting of nerve fibres with rich arborization. The tentacular ganglion near the tip of the anterior tentacle can be divided into a distal and a proximal part. The cortical layer of the ganglion contains unipolar neurons showing an uneven distribution. The well-developed neuropile is composed by sensory axons, ganglion cell processes and motor fibres of the cerebral ganglion.