PROGRAMMED CELL-DEATH IN THE MOUSE COCHLEOVESTIBULAR GANGLION DURING DEVELOPMENT

Programmed cell death (PCD) is as essential to development as is cell proliferation. Our objective was to elucidate the spatiotemporal occur rence of PCD during the development of the cochleovestibular ganglion. We performed a time-sequence study on the distribution of in situ PCD , apoptosis, during the development of the mouse cochleovestibular gan glion by using the TUNEL method to detect apoptosis histochemically. A poptosis in the cochleovestibular ganglion was observed from the 11.5t h gestational day (GD) to the 18.5th GD. Apoptosis was seen most exten sively in the vestibular ganglion cells at the 13.5th GD, while in the spiral ganglion cells apoptosis was maximal between the 15.5th and 16 .5th GD. Because these times of peak apoptotic activity almost exactly corresponded to the events of innervation and terminal mitosis of the cochleovestibular ganglion cells, we infer that PCD is involved in th e innervation and modulates the number of cochleovestibular ganglion c ells overproduced by terminal mitosis.