N-MYC EXPRESSION IN THE EMBRYONIC COCHLEA OF THE MOUSE

N-myc expression in the mouse embryo was examined during the late coch lear organogenesis. Tissue distribution of N-myc expression was histol ogically analyzed by in situ hybridization of the transcript in the co chlea between 15 and 18 days of gestation. At 15 days of gestation, N- myc expression was found very conspicuous in nervous structure of the cochlea such as the auditory nerve and the spiral ganglion. Moreover, N-myc was also present in the Kollikers organ and in the epithelium su rrounding the cochlear canal. A few days later, N-myc expression was s till clearly present in the Kollikers organ but less so in nervous str uctures. This study shows that cochlear tissues derived from the otic placode present a significant level of N-myc transcript during late em bryogenesis. N-myc expression seems to be related to cell differentiat ion in the inner ear.