Morphological characteristics of Lugaro cells in the cerebellar cortex.

Two types of Lugaro cells were identified in the cat cerebellar cortex using sections impregnated with silver nitrate by the Golgi-Kopsch method; these cells were fusiform and triangular and their bodies were located at different levels in the granular layer. Their processes were directed horizontally, vertically, or obliquely to the axis of the leaf; axons never left the cerebellar cortex. These cells should therefore be regarded as interneurons. The processes of Lugaro cells were very extended, with the result that these cells formed numerous axosomatic and axodendritic contacts with all cerebellar cortical neurons and fibers. The structural and topographical characteristics of Lugaro cells and the features of their contacts with other cells in the cerebellar cortex, taken together with data on their neurotransmitter contents, show that they function as inhibitory interneurons.