thyroid follicular cell
thyroid follicular cell
An epithelial cell that is part of the thyroid follicle epithelium, with a shape that ranges from squamous when inactive to cuboidal or columnar when active, reflecting its hormonal activity. Its apical surface is lined with microvilli projecting into the colloid-filled lumen, where it synthesizes, stores, and secretes the thyroid hormones thyroxine (T4) and triiodothyronine (T3), releasing them into the bloodstream in response to thyroid-stimulating hormone (TSH).