Age involution of thymus (human)

Stain: Azan. A: Although the adipose tissue in the thymus of a patient of 65 years is predominant it still contains areas of remnants (arrows 1+2) of cortical (2) and medullary portions (1) of the thymus. B+C: Degradation of thymic tissues is less progressed in adults and shows less replacement of thymocytes by fatty tissue (4). The cortical regions (2) are less well separated from the medullary portions (1). Distinct thymic corpuscles (Hassall) (5) of varying sizes are present. (3) capsule and interlobular septa.