Age-related reductions in number and size of anterior horn cells at C6 level of the human spinal cord.

We examined numbers and sizes of anterior horn cells (AHCs) of the human spinal cord at C6 level with aging process. Spinal cords were obtained from twenty-four male cadavers, age ranged from 41 to 97 years without any accompanying pathological changes of the spinal cord. For quantitative investigation of the AHCs, spinal cord segments were embedded in celloidin after secondary fixation and dehydration; sections (20 microns thick) were stained with luxol fast blue-periodic acid-Schiff-hematoxylin and Klüver-Barrera methods; the neuronal number, the cell body area and the perimeter of AHCs in the gray matter (equivalent to the Rexed's lamina IX) were counted and measured using a combination of a microscope with a drawing tube, a digitizer and a computer at 400 times magnification. A marked reduction in number of AHCs was found in the aged subjects. Similarly, there were significantly age-related decreases in the cross-sectional area and perimeter of AHCs at C6 segment of the spinal cord. These findings indicate that the reduction in number and size of AHCs in the human spinal cord is associated with degenerative neuronal changes and loss of motoneurons during aging process.