Age-related changes in human spinal ventral horn cells with special reference to the loss of small neurons in the intermediate zone: a quantitative analysis

A cytoarchitectonic study of spinal ventral horn cells was performed to identify age-related changes. The diameter distribution of ventral horn neurons of the fourth lumbar segment of the spinal cord and their size and topographical distributions were investigated in 14 autopsy cases. These cases represented patients of 18-100 years of age who had died of non-neurological diseases. The results indicate that small neurons widely distributed in the intermediate zone of the ventral horn significantly diminished with aging (P < 0.0005, r = -0.898), whereas medium-sized and large neurons located in the medial and lateral nuclei showed only a slight decrease with advancing age. The total number of neurons in the whole ventral horn was also noted to decrease significantly with aging (P < 0.0005, r = -0.899). While small neurons in the intermediate zone of the ventral horn are thought to be mostly interneurons, their physiological function still remains obscure in many respects. The findings of this study provide insight into age-related cell loss in terms of size and location.