Fine structure of anterior horns in patients without amyotrophic lateral sclerosis.

Light and electron microscopic study of the anterior horns in nine patients without amyotrophic lateral sclerosis (ALS) disclosed several features usually described in ALS. Central chromatolysis and spheroids with fine structure identical to that seen in ALS were observed in three cases. Rare honeycomb-like structures, dense filamentous aggregates, dense granular deposits, stubby mitochondria and membrane-bound aggregates of spherical and tubular particles were also observed. No typical Bunina bodies or focal argyrophilia of the chromatolytic neurons were found.