Hypertrophy of motor neurons in the oculomotor nucleus of the rat following removal of the contralateral extraocular muscles.

Motor neurons of the oculomotor nucleus of the rat were identified immunohistochemically using a monoclonal antibody against choline acetyltransferase (ChAT). The number and size of the cell bodies were examined following removal of the extraocular muscles on one side. 35 days postoperatively, motor neurons of the oculomotor nucleus ipsilateral to the muscle removal are undiminished in number and are of normal size when compared with littermate control animals. Cholinergic cells in the contralateral nucleus are significantly larger than normal (+23%). This hypertrophy appears to persist at least until 300 days after operation, the longest survival time examined.