Hereditary deafness in the cat. An electron microscopic study of the stria vascularis and Reissner's membrane.

The auditory pathway potentials have been recorded from a series of 35 cats, and the stria vascularis and Reissner's membrane examined with the electron microscope. The ages varied from the first postnatal day to at least 6 years. 30 of the animals had white coats, and 45 of the ears lacked potentials. The basal processes of the marginal cells fail to develop in pathological ears, and appear displaced towards the endolymphatic surface by a layer of grossly swollen, chromophobe cells. These features are already present at the 3 day stage, and persist until the third week. Thereafter, increasing electron density of all cell types is found, with progressive reduction in strial thickness. Swelling of the capillary endothelial cells and descent of Reissner's membrane are found in the first coil at 2 weeks. Obliteration of capillaries, and development of vacuolar cytoplasmic outgrowths from the vestibular membrane mesothelial cells occur at later stages. These findings are discussed and compared with the pathological changes produced by a variety of endogenous 2nd exogenous factors in both man and animals.