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Mirror Movements of Hind Limbs of the Rat with Experimentally Induced Lumbosacral Agenesis
Author(s) -
INAGE Akihiko
Publication year - 1992
Publication title -
congenital anomalies
Language(s) - English
Resource type - Journals
eISSN - 1741-4520
pISSN - 0914-3505
DOI - 10.1111/j.1741-4520.1992.tb00779.x
Subject(s) - anatomy , spinal cord , lumbosacral joint , hindlimb , conus medullaris , medicine , agenesis , psychiatry
Neuropathological and electrophysiological studies were designed to clarify the pathomechanism of motor disturbance in the hind limbs of rats with sacral agenesis. The model animals were obtained from mother rats which had been treated with trypan blue on day 8 of gestation. Mirror movements in the hind limbs were observed in 7 out of 56 rats with lumbosacral agenesis. The conus medullaris in rats with lumbosacral agenesis ended at the level between Th13‐L1 vertebra, whereas that in normal cases terminated between L3‐4. The spinal cord of the lumbosacral region was hypoplastic and dysplastic particularly in the ventral half. Anterior horn cells were sporadic and there were no apparent median fissure in the spinal cord of the lumbosacral region. On the other hand, any abnormality was not found in the brain, the brain stem, and the spinal cord of the cervicothoracic region. Horseradish peroxidase (HRP) was injected into the unilateral hind limbs. In segments of the anomalous spinal cord, HRP‐labeled neurons in the anterior horn were found not only on the injected side but also on the other side. In electrophysiological examination, F' wave was recorded on the non‐stimulated side with longer latency and duration compared with that of the stimulated side. These morphological and physiological findings indicated that the mirror movements in the hind limbs of the model animals may arise from developmental errors of motor nervous pathway, with some deficient inhibitory mechanism in the upper neural system.