Abstract
The rôle of the impulses which impinge upon the cells of the “final common pathway” in maintaining their normal functional and structural character has not been fully appreciated. Warrington 1 demonstrated that after section of the dorsal roots of the post-thoracic cord segments, anterior horn cells on the same side became structurally altered, some of them ultimately degenerating. Cells on the contralateral side were also observed to be effected in certain cord segments, apparently those concerned with crossed reflexes. These observations did not include studies of the anterior horn cells after their dissociation from impulses descending to them from higher centers. The evidence so far accumulated has not shown whether or not motor horn cells in the spinal cord are effected directly after decortication or section of the pyramidal tracts, or trans-section of the spinal cord. The following experiments were performed with this question in mind.
In the first series of 17 rats, unilateral section of the corticospinal tract on the base of the medulla was performed. The observations on the functional disorganization of these rats will be reported later. In a second series (10 rats) the dorsal roots of the fifth, sixth, seventh, eighth cervical and the first thoracic segments were sectioned; one complete root was cut in each animal. In a third series of 4 rats, double trans-sections of the spinal cord were made, one at the level of the twelfth thoracic and the second at the level of the fourth lumbar vertebra. The dorsal root fibers of both sides entering this isolated segment of the cord were also cut. The vascular system was injured as little as possible. The animals of all 3 series were killed with ether between 15 and 20 days postoperatively.
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