Thyroid and Adrenal Glands

1.1. Structure and Function of the Thyroid Gland

• Location: Anterior neck, below larynx, butterfly-shaped.
• Microscopic structure:
  • Follicles – spherical units filled with colloid (thyroglobulin).
  • Follicular cells – synthesize thyroid hormones (T₃, T₄).
  • Parafollicular (C) cells – secrete calcitonin.

• Thyroglobulin is made by the follicular cells.
• Thyroglobulin acts as the thyroid hormone synthesis and storage site
• Thyroid follicles actively accumulate iodine and secrete it into the colloid.