Undegenerated thymus gland is not an unusual and bad thing for the human body. This is because the thymus itself is an immune organ, capable of fighting pathogens that invade the organism, as well as preventing the appearance of diseases such as cancer. The thymus gland is located behind the sternum and the rib cartilage, and it usually grows at a relatively fast rate during the fetal period and about 2 years after birth under normal circumstances, and the peak of thymus growth can be reached during puberty. After puberty, the thymus gradually degenerates and atrophies and is replaced by a large amount of adipose tissue until the function of the thymus disappears completely. The main function of the thymus is to produce immunoreactive cells, such as T-lymphocytes, which are involved in cellular immunity. During the degenerative process, there is usually a decrease in the body’s cellular immunity and resistance to disease. The absence of thymus degeneration is a protective and favorable phenomenon for the human body, and is not an abnormality.