Parafollicular cell

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Parafollicular cells, also known as C cells, are specialized cells in the thyroid gland that are responsible for the production of the hormone calcitonin. These cells are located in the interstitial spaces between the thyroid follicles.

Structure

Parafollicular cells are derived from the neural crest during embryonic development. They are typically found in clusters or as individual cells within the thyroid gland. These cells are larger and paler than the surrounding follicular cells and have a high content of cytoplasmic granules that store calcitonin.

Function

The primary function of parafollicular cells is to secrete calcitonin, a hormone involved in the regulation of calcium homeostasis. Calcitonin lowers blood calcium levels by inhibiting osteoclast activity, which reduces the release of calcium from bones. It also decreases calcium reabsorption in the kidneys.

Clinical Significance

Parafollicular cells are of clinical interest because they can give rise to a type of cancer known as medullary thyroid carcinoma (MTC). MTC is a malignant tumor that originates from the parafollicular cells and is associated with elevated levels of calcitonin in the blood. Early detection and treatment are crucial for managing this type of cancer.

Histology

Under the microscope, parafollicular cells can be identified by their distinct appearance compared to follicular cells. They are larger, have a pale-staining cytoplasm, and contain numerous secretory granules. Special staining techniques, such as immunohistochemistry, can be used to highlight calcitonin within these cells.

Related Conditions

• Medullary thyroid carcinoma
• Hypercalcemia
• Hypocalcemia

See Also

• Thyroid gland
• Calcitonin
• Follicular cell
• Neural crest