Fine structure of the neurons and synapses of the vestibular ganglion of the cat.

The vestibular ganglion of 3-month-old cat was studied electron microscopically. The results revealed that the nerve cell bodies are surrounded by thin myelin sheaths which differ in some respects from typical axonal myelin. The neuronal soma displayed different cytoplasmic features and the neurons were classified into two types: light cells and dark cells. Light neurons contained individual clumps of Nissl substance distributed randomly throughout the cytoplasm, dark neurons were characterised by densely packed stacks of Nissl substance in the peripheral cytoplasm. The dark neurons of the ganglion are the only sensory neurons so far described which receive synapses.