MICROANATOMY

Detailed explanation-1: -Normal human red blood cells have an average life span of about 120 days in the circulation after which they are engulfed by macrophages. This is an extremely efficient process as macrophages phagocytose about 5 million erythrocytes every second without any significant release of hemoglobin in the circulation.

Detailed explanation-2: -Because erythrocytes and platelets do not contain a nucleus, they cannot divide to create replacements of themselves, nor can they create proteins to repair themselves when damaged. This is why erythrocytes only have a lifespan of 120 days, while platelets only live for about ten days.

Detailed explanation-3: -So, the correct answer is ‘120 days’