Development of the Thyroid Gland

The correct answer is B.

Explanation:

The thyroid gland originates as a mass of endodermal tissue near the foramen cecum, which is near the tuberculum impar (which becomes the central part of the tongue). During development, the thyroid descends in front of the pharynx, maintaining a connection to the tongue via the thyroglossal duct. Usually, the thyroglossal duct disappears.

Uncommonly, residual ectopic thyroid tissue can be left anywhere along the path, including at the back of the tongue. (In rare patients, all of the thyroid tissue remains at this site, forming a mass that should not be excised, for obvious reasons!)

The first pharyngeal pouch (choice A) develops into the middle ear and eustachian tube.
The nasolacrimal ducts (choice C) connect the eyes to the mouth.
The second pharyngeal arch (choice D) develops into many muscles of the face and styloid process of the temporal bone.
The third pharyngeal pouch (choice E) develops into the thymus and inferior glands.

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