Spinal interneuron

Abstract: Nervous centers, such as the cerebral cortex, the lateral geniculate body, the thalamus, etc., can generally be described as being built up of a number of cell layers, regions or nuclei, which are adequately characterized by the shape, arrangement and connections of their constituent cells. It is a notable fact, however, that the current descriptions of the spinal cord gray matter use its macroscopical features as the dominant principle of structural organization. Thus we have a dorsal and a ventral horn or cell column, the former has a head, a neck and a base, etc. None of these regions can be defined by cytological or cytoarchitectonic characteristics, nor is it possible to fit them into a larger cytoarchitectonic region. Microscopically only a small part of the spinal gray matter falls into well delimited cytoarchitectonic regions such as the substantia gelatinosa Rolandi or belongs to nuclei such as Clarke’s column, the motor muscle nuclei, etc. The rest of the cells are either left in macroscopically characterized regions as already noted or loosely referred to as, e.g., cells of the zona intermedia, where again no description of extent or character of the region can be given. In other regions some cells are more or less subjectively picked out from among a great number, as is the case with, for instance certain authors’ solitary