At what rate does the marrow produce erythrocytes?

1. Erythrocytes live up to 120 days and are then destroyed, so the whole population must turn over continuously. 2. Production in the marrow runs at more than 2 million cells per second. 3. That rate is what keeps the count stable at roughly 5 million cells per microlitre. 4. A rate of 2 million per minute would be sixty times too slow to replace the circulating mass in 120 days, so that option fails on arithmetic alone. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 18 "The Cardiovascular System: Blood", section 18.3 Erythrocytes_