Final answer:
Hemoglobin synthesis initiates in the rubricyte stage and concludes in the reticulocyte stage of erythrocyte development. Option b. rubricyte; reticulocyte is the correct answer to the question.
Step-by-step explanation:
Hemoglobin formation begins during the rubricyte (Proerythroblast stage) of erythrocyte maturation and ends during the reticulocyte stage. The correct answer to the question is option b. rubricyte; reticulocyte.
During erythrocyte maturation in the bone marrow, heme synthesis starts early in the stage of the rubricyte when iron is incorporated to form the heme component of hemoglobin.
As they progress to later stages, these immature red blood cells start to extrude their nucleus and synthesize heme, which then combines with the protein globin to form hemoglobin.
The final stage of hemoglobin formation occurs in the reticulocytes, which are the nearly mature red blood cells that are released into the bloodstream and continue to develop and mature into erythrocytes. The correct option is b.