Thyroid tail, and fins of tadpoles. Iodine, via iodolipids, has favored the evolution of terrestrial animal species and has likely played a crucial role in the evolution of the human brain. Thyroid The thyroid gland, or simply the thyroid, is an endocrine gland in the neck, consisting of two lobes connected by an . It is found at the front of the neck, below the Adam's apple. The thyroid gland secretes thyroid hormones, which primarily influence the metabolic rate and protein synthesis. The hormones also have many other effects including those on development. The thyroid hormones triiodothyronine (T) and thyroxine (T)
Thyroid dysgenesis arises from remnants of the thyroglossal duct, and may appear anywhere along its original length. Accessory thyroid tissue may be functional, but is generally insufficient for normal function if the main thyroid gland is entirely removed. Lingual thyroid is 4-7 times more common in females, with symptoms developing during puberty, pregnancy or menopause. Lingual thyroid may be asymptomatic, or give symptoms such as dysphagia (difficulty swallowing), dysphonia (difficulty talking) and dyspnea (difficulty breathing). Thyroid dysgenesis Thyroid dysgenesis or thyroid agenesis is a cause of congenital hypothyroidism where the thyroid is missing, ectopic, or severely underdeveloped. It should not be confused