Parafollicular cells, also called C cells, are
neuroendocrine cells in the
thyroid. They are called C cells because the primary function of these cells is to secrete
calcitonin.[1] 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. In
teleost and avian species these cells occupy a structure outside the thyroid gland named the
ultimopharyngeal body.
Structure
Parafollicular cells are pale-staining cells found in small number 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.
Development
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.[4][5] However, lineage tracing experiments in mice revealed that parafollicular cells are derived from the endoderm origin.[6]
Function
Parafollicular cells secrete
calcitonin, a hormone that participates in the regulation of
calcium metabolism. Calcitonin lowers blood levels of calcium by inhibiting the
resorption of bone by
osteoclasts, and its secretion is increased proportionally with the concentration of calcium.[7]
^Johansson, E., Andersson, L., Örnros, J., Carlsson, T., Ingeson-Carlsson, C., Liang, S., … Nilsson, M. (2015). Revising the embryonic origin of thyroid C cells in mice and humans. Development, 142(20), 3519–3528.
http://doi.org/10.1242/dev.126581
^Le Douarin N, Fontaine J, Le Lièvre C (March 1974). "New studies on the neural crest origin of the avian ultimobranchial glandular cells--interspecific combinations and cytochemical characterization of C cells based on the uptake of biogenic amine precursors". Histochemistry. 38 (4): 297–305.
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10.1007/bf00496718.
PMID4135055.
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^Melmed S, Polonsky KS, Larsen PR, Kronenberg HM (2011). Williams Textbook of Endocrinology (12th ed.). Saunders. pp. 1250–1252.
ISBN978-1437703245.
^Zabel M (December 1984). "Ultrastructural localization of calcitonin, somatostatin and serotonin in parafollicular cells of rat thyroid". The Histochemical Journal. 16 (12): 1265–72.
doi:
10.1007/bf01003725.
PMID6152264.
S2CID7889687.
Kameda Y (October 1987). "Localization of immunoreactive calcitonin gene-related peptide in thyroid C cells from various mammalian species". The Anatomical Record. 219 (2): 204–12.
doi:
10.1002/ar.1092190214.
PMID3120623.
S2CID12517073.
Baber EC (1876). "Contributions to the Minute Anatomy of the Thyroid Gland of the Dog". Philosophical Transactions of the Royal Society of London. 166: 557–568.
doi:
10.1098/rstl.1876.0021.
JSTOR109205.