Hair Cell Loss as a Function of Age in the Normal Cochlea of the Guinea Pig

Abstract

The surface specimen technique was used to study both spiral organs of 28 normal guinea pigs of 4 age groups: < 24 h, 6 wk, 3 mo. and 1 yr. Damaged hair cells were recorded for the whole of each spiral organ on cochleograms. The mean percentage number of outer hair cells damaged per age group increased as a power function of age. In the animals aged < 24 h the mean percentage of damaged outer hair cells was 0.45%; in the 6-wk animals, 1.85%; in the 3-mo. animals, 3.19%; and in the 1-yr animals, 6.82%. At all ages outer hair cell loss was maximal in the 3rd row and towards the apex of the cochlea. Inner hair cell loss was very slight, with a maximum of 9 damaged inner hair cells per cochlea.