Reticulocytes are recently produced, relatively immature red blood cells (RBCs).
Red blood cells are produced in the bone marrow, where blood-forming stem cells differentiate and develop, eventually forming reticulocytes and finally becoming mature red blood cells. They are approximately 24% higher in volume in comparison with mature RBCs. Unlike most other cells in the body, mature RBCs have no nucleus, but reticulocytes still have some remnant genetic material.
As reticulocytes mature, they lose the last residual genetic material and most are fully developed within one day of being released from the bone marrow into the blood.
The reticulocyte count or percentage is a good indicator of the ability of a person’s bone marrow to adequately produce red blood cells.
A variety of diseases and conditions can affect the production of new RBCs and/or their survival, in addition to those conditions that may result in significant bleeding. These conditions may lead to a rise or drop in the number of RBCs and may affect the reticulocyte count.