Abstract
The developmental basis of the association of congenital deafness with hypothyroidism observed in several human syndromes was earlier investigated by experiments on mice. The offspring of females with chemically induced hypothyroidism were feund to have malformations of the organ of Corti, showing that thyroxine played a role in the differentiation of this organ. The present study was undertaken to identify the site of action of the hormone in the developing organ. It appears to he the epithelium of the inner spiral sulcus.