Hereditary deafness in the cat. An electron microscopic study of the spiral ganglion.

The spiral ganglion from white cats with hereditary deafness has been studied with the transmission electron microscope, and comparisons made with hearing animals at different ages. Ganglion cell loss occurs secondary to destruction of the organ of Corti, but only after the lapse of several months. Prior to neuronal loss, the type I ganglion cells lose their myelin sheaths and concurrently develop an increased content of neurofilaments. Type I neurons transform into type II through an intermediate type III stage. This process of neurofilamentous degeneration occurs slowly, and phagocytosis is therefore an inconspicuous feature.