Electron microscopic study of the optic nerve in copper deficient rats.

The optic nerves of copper deficient rats were investigated by light and electron microscopy. Copper-deficient rats showed neurological disorders and significantly low levels of serum copper throughout the experiment (3-7 weeks). Ultrastructurally, myelin formation was extremely delayed in the postlaminar portion of the optic nerve in copper deficient rats, and myelin structures were damaged and contained many vacuoles. Swollen neurons had few neurotubules and many vacuoles in the prelaminar portion of the optic nerve. Copper deficiency appeared to cause demyelination or dysmyelination in the optic nerves of rats.