What defines a reticulocyte?

A reticulocyte is classified as an immature red blood cell. These cells are released from the bone marrow into the bloodstream and represent the body's response to increased demand for erythropoiesis, especially in conditions such as blood loss or hemolysis. The reticulocyte is characterized by the presence of residual ribosomal RNA, which is what distinguishes it from a mature red blood cell that lacks this cellular material and has a more uniform appearance.

The distinction is important clinically, as the reticulocyte count can be used to evaluate the bone marrow's function in producing red blood cells, thereby assisting in diagnosing various anemias or assessing recovery from blood loss.