Ultimopharyngeal body

The ultimopharyngeal body or ultimobranchial body or ultimobranchial gland is a small organ found in the neck region of many animals.

In humans, the ultimobranchial body is an embryological structure that gives rise to the parafollicular cells of the thyroid gland. These cells secrete the hormone calcitonin into the blood. In humans, this body is a derivative of the ventral recess of the fourth pharyngeal pouch[1] (technically fifth, but that one is rudimentary and merges with the fourth). The cells that give rise to the parafollicular cells are actually derivatives of the endoderm.[2] These cells migrate and associate with the ultimopharyngeal body during development. Failure of development of ultimobranchial body is seen in DiGeorge syndrome.