MORPHOLOGIC EVIDENCE FOR 3 CELL-TYPES IN THE HUMAN SPIRAL GANGLION

Although two types of spiral ganglion cells (large type I and smaller type II) have classically been described by anatomic studies in both a nimal and human spiral ganglion, there is physiologic and morphologic evidence for subtypes of the large type I ganglion cell. In addition, in the animal and human, a variety of morphologic differences based on cytoplasmic content, myelinization, immunostaining and morphometric a nalysis have suggested more than one variety of type I ganglion cell. Light and electron microscopic serial sections of the spiral ganglion in two human specimens in the basal, middle and upper middle turns wer e pooled for morphometric analysis of the cell area, nuclear area and axon diameter. Analysis of variance, bivariate scatter plots and multi variate cluster analysis provided evidence for 3 types of ganglion cel ls in the human spiral ganglion: large, intermediate and small, varyin g from each other significantly on the basis of cell area. It was sugg ested, based on the morphologic findings and prevalence of the cell ty pes, that the large and intermediate cells were subtypes of the classi c type I spiral ganglion cell, whereas the small ganglion cell was con sistent with the classically described type II ganglion cell.