<P> The thymus is largest and most active during the neonatal and pre-adolescent periods . By the early teens, the thymus begins to atrophy and thymic stroma is mostly replaced by adipose tissue . Nevertheless, residual T lymphopoiesis continues throughout adult life . </P> <P> The main functions of the spleen are: </P> <Ol> <Li> to produce immune cells to fight antigens </Li> <Li> to remove particulate matter and aged blood cells, mainly erythrocytes </Li> <Li> to produce blood cells during fetal life </Li> </Ol> <Li> to produce immune cells to fight antigens </Li>

What is the purpose of the lympatic system