1. Proerythroblast: This is the earliest recognizable stage of red blood cell development.

2. Basophilic erythroblast: The proerythroblast differentiates into a basophilic erythroblast, which is characterized by its large size and basophilic cytoplasm due to the presence of ribosomes.

3. Polychromatic erythroblast: The basophilic erythroblast then transitions into a polychromatic erythroblast, which shows both basophilic and acidophilic staining characteristics.

4. Normoblast: The polychromatic erythroblast further develops into a normoblast, which is smaller in size and has a more condensed nucleus.

5. Late erythroblast: The normoblast then becomes a late erythroblast, which is the final stage before the nucleus is expelled.

6. Reticulocyte: After the nucleus is ejected, the cell becomes a reticulocyte, which is characterized by the presence of a reticular network of residual RNA.

7. Mature erythrocyte: Finally, the reticulocyte matures into a mature erythrocyte, which is a fully functional red blood cell.

Therefore, the correct developmental order is: Proerythroblast, Basophilic erythroblast, Polychromatic erythroblast, Normoblast, Late erythroblast, Reticulocyte.