[Morphometric analysis in the rat spinal cord following peripheral nerve transection with the use of MAP2...

The physiological function of the spinal cord is regulated by two different kinds of information, namely, afferent inputs from the primary sensory fibers and descending inputs from the brain. The former conveys the sensory information from the peripheral region via the dorsal root ganglia to spinal interneurons or directly to motor neurons and brings about the voluntary and/or involuntary muscle movement. In the present study, the time-related changes in the dendrocytoarchitecture of the rat spinal cord following the transection of afferent and efferent connections from/to the peripheral organs were observed by using immunohistochemistry for microtubule-associated protein 2 (MAP2) and Nissl staining. To investigate the changes quantitatively, morphometric analyses were performed on the section of gray matter of tissue samples stained with MAP2-antisera. One to 24 weeks after hemitransection of the dorsal and ventral roots, a remarkable reduction in the area and progressive changes in the shape of the gray matter were seen in both the anterior and posterior horns on the lesioned side. These changes were found to be due to the reduction of the width of the anterior and posterior horns on the lesioned side rather than of the height. At the later postoperative stage, atrophy of the Fasciculus gracilis and disappearance of motoneurons on the lesioned side were recognized in Nissl stained tissue samples.