EAR MALFORMATIONS IN THE MOUSE EMBRYO FOLLOWING MATERNAL ADMINISTRATION OF TRIAZENE, WITH CLINICAL IMPLICATIONS

Triazene administration to 10-day pregnant mice gave rise to severe ea r abnormalities, including middle ear ossicle malformations. The head of the malleus and the body of the incus were sometimes absent. In som e instances, the stapes appeared dysplastic. The stapedial artery was often quite dilated, as well as other cephalic vessels, but qualitativ ely normal. Severe inner ear abnormalities were observed, as well as a uditory nerve disruption, which was associated with central nervous sy stem lesions. Multiple haematomas were present in the embryonic face, but ear abnormalities occurred even in the absence of local hemorrhage s. We postulate a direct effect of the teratogen on the branchial mese nchyme. This model seems to be useful for the comprehension of human m iddle ear abnormalities, but does not constitute a phenocopy of hemicr anial microsomia.