The cytoarchitecture of the nucleus cuneiformis. A Nissl and Golgi study.

This investigation attempts to clarify the cytoarchitectural organisation of the neurons of the nucleus cuneiformis, a reticular nucleus of the midbrain particularly involved in locomotor activities. The study was carried out on the cat and man, in Nissl and Golgi material. The nerve cell bodies, which are small or medium sized, have a light basophilic cytoplasm and a large light nucleus usually containing one nucleolus. In Golgi material multipolar and fusiform cells can be identified. Multipolar cells, which form the majority of the neural population, have 3-7 primary spiny dendrites and an axon which often projects outside the nucleus. Fusiform cells have one or two primary dendrites endowed with spines, which are, however, less numerous than those of multipolar neurons. The axons generally end inside the nucleus. The main difference between man and the cat seems to be in the length and width of the neuronal arborisation, which are considerably greater in the former species. The characteristics of the two neuronal types suggest a projective function of the multipolar elements, but an interneuronal activity of the fusiform ones. The data support the similarity already found at the ultrastructural level between the nucleus cuneiformis and the periaqueductal grey matter, but on the other hand confirm the lesser degree of cytoarchitectural complexity of the nucleus.