Electron microscopic studies of spinal ganglion cells following crushing of dorsal roots in adult rat

Abstract

Chromatolytic alterations were induced in the spinal ganglion cells of adult rats by crushing the dorsal roots of the cauda equina. The lesioned animals were sacrificed at 3, 7, 14, 21, and 28 days after lesion. Ganglia of lesioned roots were fixed in aldehydes followed by osmication. The normal ganglion cell possessed a circular or oval, centrally located nucleus. Small aggregates of free and membrane-bound ribosomes were diffusely located in the cytoplasm. Organelles, such as mitochondria, Golgi complexes, and dense bodies, were randomly located in the cell. The earliest reaction of the ganglion cell to injury was seen in the nucleus. Slight irregularity of nuclear outline was observed in 3 days and became progressively more evident by 2–3 weeks. Associated with this feature was the appearance of numerous nuclear pores. Eccentric position of the nucleus was noted by 4 weeks post-lesion. The cytoplasmic response consisted of aggregation and peripheral displacement of massive Nissl bodies. Multiple hypertrophic Golgi complexes and numerous dense bodies, presumably lysosomes, were also found in these cells. The neurofilamentous reaction was marked in the perinuclear zone as well as in the rest of the cytoplasm. Both small and large ganglion cells exhibited evidences of chromatolysis. The present studies clearly indicate that the reactive ganglion cells are capable of actively synthesizing the proteins necessary for dorsal root regeneration observed in our earlier studies.