Why Is The Nucleus Absent In Old Red Blood Cells?

It is not that a red blood corpuscle (RBC) does not ever have a nucleus. The RBC initially has a nucleus. However, as the RBC grows older, the nucleus size shrinks, and at full maturity, the nucleus vanishes. This may seem odd, considering the nucleus is considered the core of a cell. However, there is a strong reason why the nucleus disappears in older red blood corpuscles.

The RBC stores haemoglobin. Haemoglobin is a protein that keeps the oxygen bound to the RBC. When the nucleus is around, there is less space to store the haemoglobin. Once the nucleus starts shrinking, and finally vanishes, the space for haemoglobin storage, and subsequently increased oxygen levels in the blood increases. This is critical because it means that more amounts of oxygen can be transported through the blood to supply the different parts of the body. We depend on oxygen as our life source. Reduced or no nucleus essentially means more space for haemoglobin, and therefore more amounts of oxygen in the blood.