Veterinary Physiology-III

MORPHOLOGY

• In most mammals, the thyroid lies just caudal to the larynx on the first or second tracheal ring and consists of two lobes connected by a narrow isthmus.
• In birds, the thyroid gland forms two lobes lying on either side of the trachea at the level of the clavicle.
• The thyroid gland is made up of follicles filled with a material called the colloid which contains a protein - iodine complex called thyroglobulin. The thyroglobulin is secreted by the epithelial cells i.e. the follicular cells that line the follicle.