IMMUNOLOGY

Detailed explanation-1: -CAMBRIDGE, Mass. – Unlike the rest of the cells in your body, your red blood cells lack nuclei. That quirk dates back to the time when mammals began to evolve. Other vertebrates such as fish, reptiles and birds have red cells that contain nuclei that are inactive.

Detailed explanation-2: -Unlike most other eukaryotic cells, mature red blood cells don’t have nuclei. When they enter the bloodstream for the first time, they eject their nuclei and organelles, so they can carry more hemoglobin, and thus, more oxygen. Each red blood cell has a life span of around 100–120 days.

Detailed explanation-3: -They lack a cell nucleus and organelles, to accommodate maximum space for hemoglobin; they can be viewed as sacks of hemoglobin, with a plasma membrane as the sack. Approximately 2.4 million new erythrocytes are produced per second in human adults.