The developing and senescent inner ear: selected topics and models.

Abstract

Development and senescence are not mirror images, reversed, or opposite processes, but instead involve some common, as well as different mechanisms. In this review, we link the themes of development and senescence of the inner ear through the use of models. The inner ear develops in a highly coordinated series of stages. During development, each organ undergoes major structural changes prior to and during the onset of function. Thereafter, patterns of activity change as each sensory organ matures to its normal functional status. The remodeling continues at a slower pace after the onset of function. By comparison, the senescent inner ear loses its functional capacity and displays varying degrees of impairment. Cell degeneration and atrophy are commonly reported. However, in properly preserved specimens, senescent cells display few cytological markers aside from age pigment that can help to identify them.