Why the red blood cells have no nucleus?

Red blood cells have adapted this characteristic (no nucleus) for several reasons. It simply allows the red blood cell to have more hemoglobin. The more hemoglobin you have, the more oxygen molecules you can carry. Therefore, it allows RBC to transfer more oxygen. read more

Red blood cells have no nucleus, because most of their bulk is made up of hemoglobin, a compound that carries gases, such as oxygen and carbon dioxide. In fact, about a third of a red blood cell is dedicated to hemoglobin alone, so no room remains for a nucleus or many of the structures that other cells have. read more

The absence of a nucleus is an adaptation of the red blood cell for its role. It allows the red blood cell to contain more hemoglobin and, therefore, carry more oxygen molecules. It also allows the cell to have its distinctive bi-concave shape which aids diffusion. read more