X-Ray Irradiation of the Inner Ear of the Guinea Pig: An Electron Microscopic Study of the Degenerating Vestibular Sensory Cell

Abstract

The inner ear of the guinea pig was irradiated with single doses of 7000 R X-rays. An electron microscopic study of the vestibular part of the labyrinth was performed after l¹/₂, 3, 4, and 6 hours. Changes were noticed chiefly in the type II but also in some type I sensory cells. The first changes were observed in the nuclei and consisted of clumping of the chroma-tin and the interchromatinic granules and swelling of the nuclear envelope. Later the nuclei became pycnotic. In the cytoplasm the early changes were: An appearance of a large number of vacuoles with the surface studded with ribosomes, various mito-chondnal alterations, a slight increase in the number of lysosome-like bodies in the apical portion of the cells, and an appearance of sequesters of small cyto-plasmic areas dehmited by one or more layers of membranes. Severely altered cells appeared shrunken. The elimination of the degenerating cells is supposed to occur in two ways. The apical portion is expelled into the endolymph while the perinuclear portion is phagocytized by the supporting cells. Except for phagocytized material, no changes were noticed in the supporting cells.