Brain, Vol. 113, No. 2, 497-507, 1990
© 1990 Oxford University Press
research-article |
HISTOMETRIC CHARACTERISTICS AND REGENERATIVE CAPACITY IN WOBBLER MOUSE MOTOR NEURON DISEASE
Department of Neurology, The Cleveland Clinic Foundation Cleveland, Ohio, USA 1Division of Neurosurgery and Center for Neurosciences, Case Western Reserve University School of Medicine, and Cleveland VA Medical Center Cleveland, Ohio, USA
Correspondence to:
Correspondence to: Dr. Hiroshi Mitsumoto, Neuromuscular Program, Department of Neurology, The Cleveland Clinic Foundation, Cleveland, Ohio 44195. USA.
In wobbler mice, histometric features and the response to injury in the less affected hindlimb nerves were compared with the severely affected forelimb nerves which were studied previously. The frequency of vacuolated anterior horn cells was not different at the individual ages studied (3 and 6 weeks, 3 months), but with the three ages combined, the frequency in the two systems differed significantly, being 1.7±0.9% in the cervical and 0.6±0.7% in the lumbar anterior horns (P=0.005). The number of large myelinated nerve fibres (
6µm in diameter) became progressively reduced in ventral roots as the disease advanced, particularly for the forelimb. The total number of myelinated axons was well preserved in the hindlimb ventral roots because of an increase in the number of small myelinated nerve fibres. The regenerative capacity of motor neurons after axotomy (tested by radioabelling growth cones) was well preserved. In the hindlimb, the increased numbers of small myelinated fibres in ventral roots and the normal regenerative capacity in the sciatic nerve and its branches contrast with the severely affected forelimb system. Our studies suggest that cervical and lumbar anterior horn cells have different susceptibilities to the wobbler gene, producing vulnerability in one system and disease resistance in the other.
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Received April 12, 1989. Accepted June 9, 1989.
*Present addresses: Dr Kurahashi, Department of Neurology, Hirosaki University School of Medicine, Hirosaki 030, Japan; Dr Sunahara, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187, Japan.