1. The thyroid gland is a gland made up of two lobes. Each lobe is situated on the either side of the trachea. 2. The follicular cells of the thyroid gland are responsible for secretion of the thyroid hormones T3 and T4. These cells are present in the stroma. They have a substance known as colloid. 3. Exopthalmic goitre is a form of hyperthyroidism. 4. Hypothyroidism during pregnancy can cause defective foetal development.