Embryonic Development: The Formation and Incorporation of the Thyroglossal Duct by the Pharyngeal Part of the Tongue

pharyngeal part of the tonguewhich will invaginate and lead to the formation of the thyroid

The pharyngeal part of the tongue, also known as the median lingual swelling, is a structure that is present during early embryonic development

The pharyngeal part of the tongue, also known as the median lingual swelling, is a structure that is present during early embryonic development. During this stage, the tongue starts forming as a pair of lateral swellings called the lateral lingual swellings.

Around the fourth week of development, the median lingual swelling begins to form in the midline of the developing tongue. This swelling invaginates, or folds inwards, and moves downwards towards the neck region. As it descends, it overgrows a structure called the thyroglossal duct.

The thyroglossal duct is a tube-like structure that connects the developing tongue to the developing thyroid gland. It starts from the base of the tongue and extends towards the neck, where the thyroid gland will eventually form. As the pharyngeal part of the tongue invaginates, it gradually envelops and incorporates the thyroglossal duct.

During the seventh week of development, the pharyngeal part of the tongue continues its descent, carrying the thyroglossal duct with it. The thyroglossal duct ultimately becomes obliterated, meaning it disappears, while the tissue around it forms the thyroid gland.

In summary, the pharyngeal part of the tongue invaginates during embryonic development and incorporates the thyroglossal duct, which leads to the formation of the thyroid gland. This process occurs around the fourth to seventh week of development and is a crucial step in the development of the thyroid gland.

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