Autonomic neuropathy in the trembler mouse

There is little detailed histological information concerning the autonomic nervous system in hereditary demyelinating neuropathies in man. An opportunity was therefore taken to study the autonomic nervous system of the trembler mouse which suffers from a dominantly inherited peripheral neuropathy. Schwann cell myelination in trembler vagus and splanchnic nerves was abnormal. Morphometric analysis of myelinated and unmyelinated fibres in these nerves showed a marked reduction in myelinated fibre density distribution, whilst unmyelinated fibre densities were within the control range. The trembler vagus contained increased numbers of large diameter unmyelinated fibres probably as a result of trembler Schwann cell failure to form myelin around axons of the appropriate diameter for myelination. The trembler splanchnic nerve, however, contained increased numbers of small diameter unmyelinated fibres, possibly postganglionic fibres which fail to achieve their expected diameters.