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.

The cerebellar cortex contains five types of cell: stellate and basket cells in a molecular layer, Purkinje cells (piriform cells) in the piriform neuron layer, and granular cells and Golgi cells (large stellate neurons) in the granular layer [6]. All these neurons are identified in terms of their locations, sizes, and morphological characteristics. In addition to this large class of neuronal elements, there is a less numerous group of neurons in the cerebellar cortex. These cells are spindleshaped, spherical, or polygonal, and were first described by Golgi [5]. Subsequently, Lugaro [7, 8] and Ram6n y Cajal [3] described them in more detail. These cellular elements of the cerebellar cortex are known in the literature as Lugaro cells [6]. Further studies on these cells have been carried out in monkeys [4] and rats [1, 10, 11].The aim of the present study was to investigate these neurons in the cat cerebellar cortex and compare the results obtained with data from other animal species. MATERIALS AND METHODSStudies were carried out on adult cats aged 2-3 months and 2-week-old kittens. Under Nembutal (55 mg/kg) anesthesia, adult animals underwent intracardiac perfusion with 3.5% calcium bichromate in 10% neutral formalin; kittens were sacrificed under ether anesthesia. After material was processed by the method of Golgi-Kopsch, serial sections 100-200 #m thick were cut in the horizontal, sagittal, and frontal plains. Neurons were drawn with an RA--4 drawing apparatus, and microphotographs were taken using an MBI-6 microscope. RESULTS AND DISCUSSION

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