Morphology of thyroid gland:
1. Thyroid is the largest endocrine gland in the body.
2. It weighs about 25 to 30 g and measures about
5 cm in length and 3 cm in width. 3. It is located in the neck region anteriorly just below the larynx and situated ventrolaterally to the trachea.
4. The thyroid is derived from the endoderm of the embryo.
5. The thyroid can vary in size as per age, sex and diet.
6. It is reddish brown, bilobed and highly vascular
7. The two lobes are joined by connective tissue called isthmus which is located at 2nd to 4th tracheal cartilage.
8. Therefore, the right and left lobe of thyroid are seen on both sides of the trachea.
9. The gland is H-shaped having butterfly-like appearance.
10. The structural and functional units of thyroid gland are the thyroid follicles.
11. From the outer surface there lies a connective tissue capsule. A number of septa arise from the connective tissue which are called trabeculae. They divide the gland into lobules. Each lobule has follicles which store hormone. The number of follicles are about three million.
