Remyelination in the spinal cord of the cat following intraspinal injections of lysolecithin.

Intraspinal injections of small volumes of lysolecithin were made in the cat. These produced a local area of primary demyelination at the site of injection and all the demyelinated axons were subsequently remyelinated either by oligodendrocytes or Schwann cells. In general the type of remyelination depended on the position of the axon relative to the point of injection; those near the centre of the lesion were remyelinated by Schwann cells while those at the edges were remyelinated by oligodendrocytes. At the very centre of the lesion there was fairly extensive axonal degeneration. Oligodendrocyte-remyelinated axons were enclosed within astrocyte processes which were usually covered by basement membrane on the surface next to Schwann cells. The pattern of remyelination in the cat was compared with similar lesions in the rat and it was concluded that the more vigorous astrocytic response in the cat was responsible for the differences observed in the lesions in the 2 species.