Abstract
Previous studies have shown that thyroxine is one of the factors which influences fetal lung maturation. To further delineate the role of the thyroid hormones, ovine fetuses were surgically thyroidectomized at 95-99 days gestation (term gestation = 145-150 days). The thyroidectomized (Tx) and control (C) fetuses were sacrificed at 140 days. The mean serum thyroxine concentration was significantly decreased in the Tx (<1 μg%) as compared to the C (14.2 μg%). The combined heart and lung weights were significantly reduced in the Tx. Compared to the C lung, light and electron microscopic examination of the Tx lung revealed hypercellular, thickened alveolar septae and interstitium. The Tx lung alveolar lining consisted of cuboidal cells without the characteristic lamellar bodies and the tracheal fluid lecithin/sphingomyelin ratio was decreased, indicative of delayed surfactant synthesis. The DNA content was increased and protein/DNA ratio reduced per gram wet weight lung tissue in the Tx, indicating that compared to the C, there was a larger number of smaller sized cells. Thus, it appears that thyroidectomy in the ovine fetus during the second trimester significantly delays lung maturation and surfactant synthesis. Further studies are needed to define the role of the human fetal and neonatal hypothalamic-pituitary-thyroid axis in the idiopathic respiratory distress syndrome.
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Erenberg, A., Rhodes, M., Weinstein, M. et al. THE EFFECT OF FETAL THYROIDECTOMY ON OVINE FETAL LUNG MATURATION. Pediatr Res 11, 425 (1977). https://doi.org/10.1203/00006450-197704000-00338
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DOI: https://doi.org/10.1203/00006450-197704000-00338