Mice of the Bar Harbor 129 Re dydy strain suffer from a progressive degeneration of the skeletal muscles similar in pathological characteristics to that of human Duchenne muscular dystrophy. Previously the nervous system of these animals has been described as being without abnormality. This report details striking abnormalities of the dorsal and ventral roots and proximal parts of the sciatic nerves of these animals. The abnormalities consist of non-myelinated axons of up to 6 μ diameter, without surrounding Schwann cell cytoplasm, collected into extensive areas between a few relatively normal myelinated axons. These areas are surrounded by sheets of Schwann cells, which show the morphological counterparts of active metabolism, and some of which show attempted myelination of axons. These abnormalities are equally extensive in older and in younger animals, though the appearance is very similar to that of foetal developing nerve. Minor evidence of axonal degeneration is present. The changes are interpreted as indicating a developmental abnormality of myelination by Schwann cells, perhaps as a result of the impaired mitotic division of these cells. They offer an experimental model for the investigation of a number of problems of nerve physiology. Preliminary studies of peripheral nerve and nerve roots from human cases of Duchenne muscular dystrophy and from dystrophic hamsters have not revealed a similar abnormality. The change is therefore likely to be a phenomenon confined to the dystrophic mouse, and one which is unrelated to the coexisting skeletal muscle degeneration.
ASJC Scopus subject areas
- Clinical Neurology