Vandernoot I, Sartelet H, Abu-Khudir R, Chanoine JP, Deladoëy J. Evidence for calcitonin-producing cells in human lingual thyroids. J Clin Endocrinol Metab 2012; 97: 951-956.

A lingual thyroid results from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Fusion of the ultimobranchial bodies (from which the calcitonin-producing cells derive) with the thyroid occurs when migration is almost completed. Therefore, calcitonin-producing cells are not expected to be present in lingual thyroids. Here, we report evidence of calcitonin producing cells in four independent cases of lingual thyroids. This suggests that the ultimobranchial bodies are not the only source of calcitonin-producing cells in humans. Interactions between calcitonin-producing and thyroid follicular cells occur earlier than previously accepted.