What is ultimobranchial body?

The ultimobranchial body is a small, bilaterally symmetrical endocrine gland that is found at the base of the embryonic thyroid gland in vertebrates. It is primarily responsible for the production and secretion of calcitonin, which helps regulate calcium levels in the blood. The ultimobranchial body is derived from neural crest cells and is also known as the C cells, parafollicular cells, or the fifth thyroid or parathyroid gland. Dysfunction or abnormality of the ultimobranchial body can result in a variety of disorders, including thyroid cancer or hypocalcemia.