Final answer:
Packed red blood cells are stored in citrate-phosphate-dextrose with a shelf life of 42 days. They have a circulation lifespan of 120 days in the body, after which they are recycled by macrophages.
Step-by-step explanation:
Packed red blood cells (PRBCs) are stored in a preservative solution known as citrate-phosphate-dextrose, which helps to maintain their viability and function. The shelf life of PRBCs under these storage conditions is approximately 42 days. Red blood cells are responsible for the transport of oxygen and, once transfused, they can serve their purpose in the recipient's circulation for a time. Reticulocytes, which are immature red blood cells, are released into the bloodstream and mature into erythrocytes, which have an average lifespan of 120 days in the body. Erythrocytes are then phagocytized by macrophages in the liver and spleen once they reach the end of their lifespan.