MICROANATOMY

Detailed explanation-1: -The thymus continues to grow after birth reaching the relative maximum size by puberty. It is most active in fetal and neonatal life. It increases to a mass of 20 to 50 grams by puberty. It then begins to decrease in size and activity in a process called thymic involution.

Detailed explanation-2: -The thymus is a vital yet unusual organ. Vital in that it is responsible for producing immune cells; unusual in that it is largest at childhood and progressively shrinks after puberty.

Detailed explanation-3: -Thymic Involution: The thymus gland begins to steadily decline in size and function after the completion of puberty. Over time, the cells of the thymus are replaced with fat cells. This process is called thymic involution.

Detailed explanation-4: -Thymic involution is the genetically programmed aging process via which the thymus undergoes a progressive reduction in size due to the loss of thymic epithelial cells and decrease in thymopoiesis (Bar-Dayan, Afek, Bar-Dayan, Goldberg, & Kopolovic, 1999; Taub & Longo, 2005).

Detailed explanation-5: -The thymus produces and secretes thymosin, a hormone necessary for T cell development and production. The thymus is special in that, unlike most organs, it is at its largest in children. Once you reach puberty, the thymus starts to slowly shrink and become replaced by fat.