Mention the location of the thymus gland in the body and state its importance.

(N/A) The thymus gland is a lobular structure located between the lungs, behind the sternum, on the ventral side of the aorta.
The thymus plays a major role in the development of the immune system.
The thymus gland secretes a peptide hormone called thymosins.
Thymosins play a major role in the differentiation of $T$-lymphocytes, which provide cell-mediated immunity.
Thymosins also promote the production of antibodies to provide humoral immunity.
The thymus degenerates in old individuals, resulting in a decreased production of thymosins. As a result, the immune responses of old persons become weak.