Which sequence correctly lists the stages from Proerythroblast to Reticulocyte in the ERYTHRO- progression?

• A. Proerythroblast → Basophilic erythroblast → Polychromatic erythroblast → Reticulocyte → Orthochromatic erythroblast
• B. Proerythroblast → Basophilic erythroblast → Orthochromatic erythroblast → Polychromatic erythroblast → Reticulocyte
• C. Proerythroblast → Basophilic erythroblast → Polychromatic erythroblast → Orthochromatic erythroblast → Reticulocyte
• D. Proerythroblast → Polychromatic erythroblast → Basophilic erythroblast → Orthochromatic erythroblast → Reticulocyte

Answer: (C)

The sequence reflects how red blood cell precursors mature during erythropoiesis, shown by changing cytoplasm color and the nucleus. Early stages have very RNA-rich, basophilic cytoplasm; as hemoglobin builds up, the cytoplasm shifts toward a lighter, more pinkish tone; the nucleus becomes smaller and is eventually extruded to form a reticulocyte.

So the correct order is: Proerythroblast, then Basophilic erythroblast, followed by Polychromatic erythroblast, then Orthochromatic erythroblast, and finally Reticulocyte. This mirrors the increasing hemoglobin content and the eventual release of the cell into circulation as a reticulocyte, which still contains residual RNA.

Other sequences misplace the later stages relative to the maturation markers (for example, placing the reticulocyte before the orthochromatic stage), which doesn’t fit how Hb accumulation and nuclear extrusion occur during development.