SELECTIVE DESTRUCTION OF LARGE MOTONEURONS BY POLIOMYEITIS VIRUS II. SIZE OF MOTONEURONS IN THE SPINAL CORD OF RHESUS MONKEYS

Abstract

The size distribution has been studied of the motoneurons of the anterior horns of 6 normal monkeys and 3 animals in the chronic stage of experimentally induced poliomyelitis. Cords from the infected animals show a greater proportion of small neurons and a smaller proportion of large cells than do normal cords. The relative preponderance of small neurons and the paucity of large cells increase with the severity of the lesion. The abundance of small motor nerve cells and scarcity of large ones is due to the fact that the virus of poliomyelitis first singles out for destruction the large motoneurons and leaves the small cells relatively intact. As the disease process increases in intensity the small neurons are also destroyed.