Ganglion cell and hair cell loss in Coturnix quail associated with aging

Hair cells and ganglion cells were examined in young adult (3 month old) and senescent (3 to 6 year old) quail (Coturnix coturnix). Following sacrifice the basilar papillae, along with the ganglia, were fixed, embedded in plastic and sectioned serially at 100 micron intervals from basal to apical tip. Hair cells and ganglion cells were counted from three micron thick sections at each interval. Hair cell number remained constant between age groups (less than 10% loss even in the oldest group). Ganglion cell number, on the other hand, was considerably reduced in the senescent birds (20-60% loss). These results are similar to quantitative results in senescent mammals and suggest that ganglion cell loss may be generalized response to aging.