Diabetic autonomic neuropathy in BB rat. Ultrastructural and morphometric changes in parasympathetic nerves.

Longitudinal electron-microscopic and morphometric studies of autonomic nerves containing predominantly parasympathetic fibers were undertaken in the spontaneously diabetic BB rat. Unmyelinated fibers of the diabetic vagus nerve and myelinated fibers of the penile nerve showed increased numbers of axonal glycogenosomes and axonal sequestration. Morphometric examination of myelinated and unmyelinated fibers of the vagus nerve revealed diminished fiber size compared with age-matched control animals. The distal myenteric nerve showed marked degenerative changes, whereas no structural changes could be demonstrated in intra-myenteric ganglion cells. These changes are similar to those described previously in somatic nerves of this model but different from those seen in sympathetic nerves of the diabetic BB rat.