ANATOMY

Detailed explanation-1: -– 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: -Mammal red blood cells (erythrocytes) contain neither nucleus nor mitochondria. Traditional theory suggests that the presence of a nucleus would prevent big nucleated erythrocytes to squeeze through these small capillaries. However, nucleus is too small to hinder erythrocyte deformation.

Detailed explanation-3: -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.

Detailed explanation-4: -Specifically, mature red blood cells and cornified cells in the skin, hair, and nails contain no nucleus.

Detailed explanation-5: -Red cells do not normally contain a nucleus and are unable to proliferate. They have a limited life-span ( 120 days in humans) and are replenished by the constant generation of new cells from hematopoietic stem/progenitor cell compartments.