Following on from a recent post on the involution of the thymus in adults, the process by which it ceases to generate immune cells and atrophies, here is a another paper that considers some of the possible paths to interventions that maintain the thymus into old age. Given experiments in mice showing that transplant of a young thymus extends life, this seems worthy of further investigation: "The thymus is the primary organ for T-cell differentiation and maturation. Unlike other major organs, the thymus is highly dynamic, capable of undergoing multiple rounds of almost complete atrophy followed by rapid restoration. The process of thymic atrophy, or involution, results in decreased thymopoiesis and emigration of naïve T cells to the periphery. Multiple processes can trigger transient thymic involution, including bacterial and viral infection(s), aging, pregnancy and stress. Intense investigations into the mechanisms that underlie thymic involution have revealed diverse cellular and molecular mediators, with elaborate control mechanisms. This review outlines the disparate pathways through which involution can be mediated, from the transient infection-mediated pathway, tightly controlled by microRNA, to the chronic changes that occur through aging."