PROGRAMMED CELL-DEATH IN THE DEVELOPING EPITHELIUM OF THE MOUSE INNER-EAR

Programmed cell death is as essential to development as is proliferati on. Thus, the objective of this study was to elucidate the spatiotempo ral involvement of programmed cell death in the development of the inn er ear epithelia. Programmed cell death is seen in situ as apoptosis. A time-sequence study was performed on the distribution of apoptosis d uring the development of the inner ear epithelia of the mouse using th e TdT-mediated dUTP-biotin nick labeling (TUNEL) method to detect apop tosis histochemically. Apoptosis occurred during the early stages of d evelopment of the inner ear and took place earlier in the organs of eq uilibrium than in the cochlea. These periods corresponded to those of active proliferation of epithelial cells in the inner ear. Since cell- cell interactions change after the removal of neighboring cells by apo ptosis, apoptosis may influence cytodifferentiation.