Congenital malformations of middle and inner ears of parabiotic twins

We describe herein the congenital malformations of the middle and inner ear s in temporal bones of parabiotic, monozygotic twins. Temporal bones were r emoved from twin B, who had no fetal cardiac activity and was born dead at 23-4/7 weeks, and twin A, the donor or "pump" twin in intrauterine life, wh o died shortly after birth at 20-6/7 weeks. The temporal bones were process ed routinely in celoidin, stained with hematoxylin and eosin, and examined by light microscopy. We found that twin B had Mondini's dysplasia with asso ciated deformities of the middle ear and in general showed more development al anomalies than twin A, and we conclude that Mondini's dysplasia with ano malies of the middle ear may occur in the parabiotic twin syndrome, and the abnormalities may be explainable as the result of vascular disturbance, wh ich also causes other lesions in these unusual cases.