The ventral dendritic arbor of marginal (lamina I) neurons in the adult primate spinal cord.

The ventral (gelatinosal) dendritic arbor of marginal neurons taken from lumbosacral cord was examined in Golgi preparations from adult Macaque monkey and adult Squirrel monkey where neurons were filled with horseradish peroxidase (HRP) via secondary diffusion. Based on morphological criteria two types of marginal neurons were found which give rise to a substantial ventral dendritic arbor. These dendrites penetrate the depth of lamina II and some extend well into lamina III. The cell bodies are medium to large in size and confined to the medial half of lamina I. Marginal neurons located in the lateral half of the marginal layer lack gelatinosal dendrites and are characterized instead by numerous interstitial dendrites.