Key result
Hypothyroidism induced by propylthiouracil in rat pups resulted in severe abnormalities in the organ of Corti, including prolonged persistence of Kölliker's organ and marked signs of immaturity.
Hypothyroidism during early development in rats causes severe structural abnormalities and maturation retardation in the organ of Corti, potentially accounting for hearing loss.
Caution against extrapolating rat findings to human neonates; leaves open mechanistic role of hypothyroidism in congenital hearing loss.
The structural development of the organ of Corti was studied in 30 rat pups rendered hypothyroid by daily administration of propylthiouracil during the first 35 days after birth. Cochlear changes were observed by light microscopy and electronmicroscopy. Hypothyroid rat pups were found to have severe abnormalities in the organ of Corti. There was an abnormally prolonged persistence of Kölliker's organ and striking distortion of the tectorial membrane. The sensory epithelium exhibited marked signs of immaturity: the tunnel of Corti has not opened yet in animals 35 days old, sensory and supporting cells presented immature characteristics with abnormal persistence of the kinocilium. It is suggested that hypothyroidism results in an overall retardation of the maturation of cochlear structures and ultrastructural changes that appear to be significant enough to account for the hearing loss.
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Uziel et al. (1981) studied Hypothyroidism (n=30). Propylthiouracil was evaluated on Structural development of the organ of Corti. Hypothyroidism induced by propylthiouracil in rat pups resulted in severe abnormalities in the organ of Corti, including prolonged persistence of Kölliker's organ and marked signs of immaturity.
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