[Experimental study on the etiology of idiopathic scoliosis--a deviation of lower motor neurons of the spinal muscle detected by the horseradish peroxidase method].

In order to elucidate the etiology of idiopathic scoliosis, studies were carried out by HRP method on the topographical localization and numerical alteration of spinal motor neurons innervating the spinal muscle of the non-scoliotic Japanese quail and the scoliotic one established by S. Hijikata in 1976. The topographical localization of spinal motor neurons innervating the triceps brachii muscle of the both groups, furthermore, was examined by the same method, and the anatomical fiber connection between the spinal motor neurons and the related spinal muscles was studied by central chromatolysis method. In addition the motor end-plate of the spinal muscle, found as an activated precipitate of AchE, was studied. In these studies on the anatomical fiber connection between the spinal motor neurons and the related spinal muscles, the retrograde axonal transport of HRP in the triceps brachii muscle, characterized by the phasic muscle, and the motor end-plate of the spinal muscle, there was no difference was found between the two groups. On the other hand, the retrograde axonal transport of HRP in the spinal muscle, characterized by the tonic muscle, was distinctly reduced in the scoliotic group, but it did not correlate with an angle of scoliotic curvature and the duration of scoliotic deformity. Reduction of the retrograde axonal transport should be regarded as primary neurogenic change, related with causation of idiopathic scoliosis.