Thyroid Parenchyma: Structure, Function & Hormones

The thyroid parenchyma consists of follicles, which are the structural and functional units of the thyroid gland. Each follicle is composed of a single layer of cuboidal epithelial cells surrounding a central lumen filled with colloid, a protein-rich fluid that contains the thyroid hormones thyroxine (T4) and triiodothyronine (T3). The epithelial cells of the follicles synthesize, store, and release these hormones into the bloodstream.

Thyroid parenchyma makes up the bulk of the thyroid gland and is responsible for the gland's primary function, which is the production and release of thyroid hormones. The hormones regulate various metabolic processes in the body, including growth, development, and energy production.