Morphology and ultrastructure of an identified histamine-containing neuron in the central nervous system of the pond snail, Lymnaea stagnalis L.

An identifiable histamine-containing neuron is located on the anterior dorsal surface of the visceral ganglion of Lymnaea stagnalis L. After [3H]histamine was injected into the perikaryon of this neuron, labelled axonal ramifications were seen in the neuropils of all ganglia except the pedals and right cerebral, and labelled axons occurred in seven nerve trunks. Electron microscopical examination of the perikaryon of the histamine neuron revealed the presence of large aggregations of granulated vesicles (80-200 microns diameter), elaborate endoplasmic reticulum, and numerous mitochondria, Golgi complexes and lysosome-like organelles.