Search results
Results from the WOW.Com Content Network
Thyroid follicular cells form a simple cuboidal epithelium and are arranged in spherical thyroid follicles surrounding a fluid filled space known as the colloid. The interior space formed by the follicular cells is known as the follicular lumen .
A follicle is formed by a spherical arrangement of follicular cells. The follicular lumen is filled with colloid, a concentrated solution of thyroglobulin and is the site of synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). [16] Parafollicular cells. Scattered among follicular cells and in spaces between the spherical ...
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.
The thyroid hormones cross the follicular cell membrane towards the blood vessels by an unknown mechanism. [31] Text books have stated that diffusion is the main means of transport, [45] but recent studies indicate that monocarboxylate transporter (MCT) 8 and 10 play major roles in the efflux of the thyroid hormones from the thyroid cells. [32 ...
Thyroglobulin (Tg) is a 660 kDa, dimeric glycoprotein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Tg is secreted and accumulated at hundreds of grams per litre in the extracellular compartment of the thyroid follicles, accounting for approximately half of the protein content of the thyroid gland. [5]
This occurs through stimulation of six steps in thyroid hormone synthesis: (1) Up-regulating the activity of the sodium-iodide symporter (NIS) on the basolateral membrane of thyroid follicular cells, thereby increasing intracellular concentrations of iodine (iodine trapping). (2) Stimulating iodination of thyroglobulin in the follicular lumen ...
After entering the thyroid follicle (or thyroid follicular cell) via a Na + /I − symporter (NIS) on the basolateral side, iodide is shuttled across the apical membrane into the colloid via pendrin after which thyroid peroxidase oxidizes iodide to atomic iodine (I) or iodinium (I +). The chemical reactions catalyzed by thyroid peroxidase occur ...
Once inside the follicular cells, the iodide diffuses to the apical membrane, where it is metabolically oxidized through the action of thyroid peroxidase to iodinium (I +) which in turn iodinates tyrosine residues of the thyroglobulin proteins in the follicle colloid. Thus, NIS is essential for the synthesis of thyroid hormones (T 3 and T 4). [14]