They form the single layer of cuboidal epithelium that makes up the outer structure of the almost spherical thyroid follicle.

The basolateral membrane of follicular cells contains thyrotropin receptors which bind to thyroid-stimulating hormone (TSH) found circulating in the blood.

Their embryologic origin is from a median endodermal mass in the region of the tongue (foramen cecum) in contrast to parafollicular cells which arise from the 4th pharyngeal pouch.

These thyroid hormones are transported throughout the body where they control metabolism (which is the conversion of oxygen and carbohydrates to energy).

The transport of iodide into follicular cells is vital for the synthesis of the iodine containing thyroid hormones.