Essential organ of immunity, that no longer works even in childhood The thymus is the organ shown in the animation☝🏻 The maturation, differentiation and immunological "training" of T-lymphocytes takes place in it. Why do children have a thymus and then gradually lose it as they get older? This organ is only necessary to create "initial" immunity. To build it up from scratch after birth🙌🏻 During puberty, the body itself deprives the thymus of blood supply, causing its tissue to lose its "immunological" function. Interestingly, some scientists attribute the decrease in immunity to the final disappearance of the thymus, among other things.