Final answer:
Old erythrocytes are destroyed by macrophages mainly in the spleen and liver after around 120 days in circulation, with their components being recycled.
Step-by-step explanation:
Old and damaged erythrocytes, also known as red blood cells (RBCs), are primarily destroyed in the spleen, liver, and bone marrow. These erythrocytes typically have a lifespan of up to 120 days in circulation before they are taken out of commission. The process of eliminating these cells is conducted by specialized cells called macrophages. The macrophages engulf (through a process known as phagocytosis) the old RBCs, breaking them down and recycling their components. This breakdown process is essential for maintaining healthy levels of erythrocytes in the body and avoiding complications such as jaundice or anemia.