Organ which undergoes involution: March 2005

Ans. D: ThymusOne of the major characteristics of veebrate immunology is thymic involution, the shrinking of the thymus with age, resulting in changes in the architecture of the thymus and a decrease in tissue mass.This process has been conserved in almost all veebrates, from birds, teleosts, amphibians to reptiles, though the thymuses of a few species of sharks are known not to involute.Since the thymus is the organ responsible for T-lymphocyte (T cell) maturation, its regression has been linked to the reduction in immunosurveillance in the elderly.Though thymic involution has been linked to senescence, it is not induced by senescence as the organ stas involuting from a young age - as early as the first year of life in humans