Examination of some morphological properties and axonal pathways of giant neurones in the central nervous system of Lymnaea stagnalis

Abstract

1. 1. In the central nervous system of Lymnaea stagnalis some of the neurones identified earlier on the basis of the activity pattern were stained by intracellular injection of CoCl 2. Retrograde staining was carried out through the main nerves originating in the visceral and right parietal ganglia. 2. 2. Recordings were made from the neurones with microelectrodes and the correlation between their activity pattern and the extracellular signals in the nervus intestinalis, nervus analis and nervus pallialis dexter recorded with suction electrode was examined. On the other hand upon stimulating these nerves the evoked responses in the soma of neurones were recorded. 3. 3. A map was constructed demonstrating the axonal pathways of neurones. Most of the neurones are pseudounipolar and their axons make connections between two or three ganglia. Some of the axonal branches run into one of the three nerves, however neurones having direct axonal connections with two nerves were also found, another cells had no direct peripheral output. 4. 4. Conclusions were drawn about the probable functional role of the neurones examined. Three main type of neurones were distinguished: (a) motoneurones playing simple and integrative function; (b) sensory neurone; (c) neurones having no peripheral output, that might take part in the interganglionic integrative processes.