Parafollicular cell
Encyclopedia
Parafollicular cells are cells in the thyroid
that produce and secrete calcitonin
. They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells or colloid. In teleost and avian species these cells occupy a structure outside of the thyroid gland named the ultimobranchial body.
In a series of elegant experiments, Nicole LeDouarin (ref), transplanted neural crest cells from quail, with unique and easily identified nuclei, into non-quail neural crest. She subsequently demonstrated the presence of cells with quail nuclei populating the ultimobranchial body and concluded that C cells migrate during embryologic development from the neural crest.
Embryologically, they associate with the ultimobranchial body
, which itself is a ventral derivative of the fourth (or fifth) pharyngeal pouch
. Parafollicular cells themselves are derived from Neural Crest
cells. They are not numerous in the thyroid and are typically situated basally in the epithelium, without direct contact with the follicular lumen. They are always situated within the basement membrane
, which surrounds the entire follicle.
When parafollicular cells become cancerous, they lead to medullary carcinoma
of the thyroid.
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
that produce and secrete calcitonin
Calcitonin
Calcitonin is a 32-amino acid linear polypeptide hormone that is producedin humans primarily by the parafollicular cells of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium , opposing the effects of parathyroid hormone . Calcitonin has been found...
. They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells or colloid. In teleost and avian species these cells occupy a structure outside of the thyroid gland named the ultimobranchial body.
In a series of elegant experiments, Nicole LeDouarin (ref), transplanted neural crest cells from quail, with unique and easily identified nuclei, into non-quail neural crest. She subsequently demonstrated the presence of cells with quail nuclei populating the ultimobranchial body and concluded that C cells migrate during embryologic development from the neural crest.
Embryologically, they associate with the ultimobranchial body
Ultimobranchial body
The ultimopharyngeal body or ultimobranchial body or ultimobranchial gland is a small organ found in the neck region of many animals....
, which itself is a ventral derivative of the fourth (or fifth) pharyngeal pouch
Pharyngeal pouch
Pharyngeal pouch can refer to:* Zenker's diverticulum* Pharyngeal pouch...
. Parafollicular cells themselves are derived from Neural Crest
Neural crest
Neural crest cells are a transient, multipotent, migratory cell population unique to vertebrates that gives rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia....
cells. They are not numerous in the thyroid and are typically situated basally in the epithelium, without direct contact with the follicular lumen. They are always situated within the basement membrane
Basement membrane
The basement membrane is a thin sheet of fibers that underlies the epithelium, which lines the cavities and surfaces of organs including skin, or the endothelium, which lines the interior surface of blood vessels.- Composition :...
, which surrounds the entire follicle.
When parafollicular cells become cancerous, they lead to medullary carcinoma
Medullary thyroid cancer
Medullary thyroid cancer is a form of thyroid carcinoma which originates from the parafollicular cells , which produce the hormone calcitonin....
of the thyroid.
Literature
- Baber EC: Contributions to the minute anatomy of the thyroid gland of the dog. Phil Trans R Soc 166 (1876) 557-568 (full text)