Apoptosis during inner ear development in human and mouse embryos: an analysis by computer-assisted three-dimensional reconstruction

Apoptosis in the developing inner ear tissue of human (Carnegie stage 14 to 21, approximately 5 to 8 weeks of gestation) and mouse (10.5 to 14 days of gestation) embryos was systematically analyzed by a computer-assisted thre e-dimensional reconstruction of the serial histological sections and by the TUNEL method. Morphogenetic events such as folding between the utricular p ortion and endolymphatic duct, constriction of the junction of the saccule with the cochlea and folding of the vestibular portion to form the semicirc ular ducts were accompanied by a localized distribution of apoptosis. The a poptosis was also related to the innervation of the cochlear and vestibular epithelia from the sensory ganglion of the eighth cranial nerve and the di fferentiation of the otic epithelia into the sensory epithelia. These resul ts suggest that apoptosis plays an important role in the development of the inner ear.