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Parafollicular cells are derived from pharyngeal endoderm. [2] [3] Embryologically, they associate with the ultimopharyngeal body, which is a ventral derivative of the fourth (or fifth) pharyngeal pouch. Parafollicular cells were previously believed to be derived from the neural crest based on a series of experiments in quail-chick chimeras.
The neuroendocrine parafollicular cells, also known as C cells, responsible for the production of calcitonin, are derived from foregut endoderm. This part of the thyroid then first forms as the ultimopharyngeal body , which begins in the ventral fourth pharyngeal pouch and joins the primordial thyroid gland during its descent to its final location.
Calcitonin-producing parafollicular cells are also found along the basement membrane of the thyroid follicle, interspersed between follicular cells; and in spaces between the spherical follicles. Parafollicular cells can be distinguished from follicular cells based on their lighter staining cytoplasm using H&E .
Follicular cell; Parafollicular cell [3] Parathyroid gland. Parathyroid chief cell; Oxyphil cell; Thymus gland. Thymic epithelial cell; Hindgut/cloaca.
superior parathyroid glands and ultimobranchial body which forms the parafollicular C-Cells of the thyroid gland. Musculature and cartilage of larynx (along with the sixth pharyngeal arch). Nerve supplying these derivatives is Superior laryngeal nerve.
It develops into the parafollicular cells of the thyroid. [2] The cells that give rise to the parafollicular cells are derivatives of endoderm. [3] Endoderm cells migrate and associate with the ultimopharyngeal body during development.
Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates [5] in the ultimopharyngeal body. [6] It acts to reduce blood calcium (Ca 2+), opposing the effects of parathyroid hormone (PTH). [7]
Calcitonin, produced by the parafollicular cells (C cells) of the thyroid gland in response to rising blood calcium levels, depresses blood calcium levels by inhibiting bone matrix resorption and enhancing calcium deposit in bones. Excessive secretion cause hyperthyroidism and deficiency cause hypothyroidism.