Final answer:
The thymus gland, positioned behind the sternum in the chest, is where T cells mature and where thymosin hormones are produced, aiding in the development of the adaptive immune system.
Step-by-step explanation:
T cells mature in the thymus gland, which is an essential organ of the lymphatic system. It is a bilobed structure located in the chest, specifically in the space between the sternum and the aorta of the heart. Inside the thymus, thymosin hormones are produced, which are crucial for the development of the body's immune system.
T cells are critical components of the adaptive immune system; they adapt to specific pathogens and play a vital role in immune response. Furthermore, the thymus gland stores lymphocytes as they mature, being most prominent in infants and decreasing in size as one reaches adulthood.