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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Persistent thyroglossal duct ： ウィキペディア英語版 Persistent thyroglossal duct A persistent thyroglossal duct is a usually benign medical condition in which the thyroglossal duct, a structure usually only found during embryonic development, fails to atrophy. The duct persists as a midline structure forming an open connection between the back of the tongue and the thyroid gland.This opening can lead to fluid accumulation and infection, which necessitate the removal of the duct. ==Embryological origin== During the third week of development, the thyroid gland begins to develop from the floor of the pharynx. This primordium begins as an evagination between the first and second pharyngeal grooves, relatively where the anterior two-thirds of the tongue ends. This area is known as the foramen cecum and marks the origin of the thyroglossal duct. As the developing thyroid begins to travel to its intended destination, it remains connected to the tongue via the thyroglossal duct. By the seventh week of fetal development, the thyroid reaches its final position in the neck after growing through the mesoderm and musculature of the tongue, mouth, and neck. During the eighth to tenth week, the cells of the duct normally begin growing inwards and fill the previously hollow tube, beginning from the inferior end. This inferior end of the duct will then become the pyramidal lobe of the thyroid gland. The dividing cellular cords of the tubular duct become the isthmus and lateral lobes of the gland to complete the formation of the rest of the gland. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Persistent thyroglossal duct」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.