What is a reticulocyte?

• A. An immature red blood cell
• B. A mature white blood cell
• C. A platelet
• D. A stem cell

Answer: (A)

Reticulocytes are immature red blood cells released from the bone marrow. They still contain residual RNA, which forms a tiny, net-like network seen with special stains. This means they are young erythrocytes on their way to becoming fully mature, disk-shaped red cells that lack a nucleus. The presence and number of reticulocytes in the blood reflect how well the bone marrow is responding to RBC loss or destruction—if the count is higher, the marrow is actively producing red cells; if it’s low, production may be inadequate.

That’s why the correct description is an immature red blood cell. A mature white blood cell is a leukocyte, a platelet is a small cell involved in clotting, and a stem cell is an early progenitor that can give rise to multiple lineages, not a partially developed red cell.