**3. Thymic function and age**

Thymus functionality starts during fetal life and is maximal at birth. After the first year of life, thymus goes through a chronic atrophy that progressively diminishes its function, eventually leading to thymic function exhaustion in later life. During this process TES loses the cortical/medullar architecture, lymphoid components are greatly reduced and TCR rearrangement is somehow impaired. Besides, TES is progressively reduced and this space is filled with adipocyte-packed PVS. Clinical implications of the age-related loss of thymic function and the specific burden of thymic output during different life-stages are still controversial.


Table 1. Advantages and disadvantages of the different thymic function quantification methods
