The thymus is the training center of the T cells, among which the immune system recruits some of its defense battalions. There the T cells are trained for their imminent duties as “killer cells”, “helper cells”, “memory cells” and “regulatory T cells”.

The thymus is located behind the sternum, above the heart. At the time of birth and during infancy, the thymus is fully developed. In adolescents it is already degenerating, until finally, it only retains a few residues of medullar tissue and cortical tissue.

In addition, the thymus is also a gland. As a gland, the thymus produces messenger substances which control the development of certain defense cells within the immune system.