A neuropathy in goats caused by experimental coyotiool (Karwinskia humboldtiana) poisoning. II. Lesions in the peripheral nervous system--teased fiber and acid phosphatase studies.

The sequential development of the lesions in the peripheral nervous systems of 22 goats poisoned with daily oral doses of ground coyotillo fruits was studied. Studies of teased fibers revealed swelling of Schwann cells, clefts in the myelin sheath, segmental demyelination, remyelination, Wallerian degeneration, and regeneration. A few fibers had a large globular or ovoid swelling in a transitional zone between a region undergoing segmental demyelination at one end and Wallerian degeneration at the other end. These distended transitional zones were the sites of intense acid phosphatase activity in axons.These histologic studies indicate that the primary lesion occurred in Schwann cells and resulted in swelling of Schwann cells, clefts in the myelin sheath, and segmental demyclination. The sequence of development of the lesions suggests that axonal degeneration were secondary to Schwann-cell injury.