This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Haemoglobin first appears in which stage of erythropoiesis? 
Select and explain. 
A. Basophil erythroblast, B. Proerythroblast, C. Ohochromatic erythroblast, D. Polychromatophil erythroblast
A: Basophil erythroblast
Answer: A: Basophil erythroblast 
Explanation: Once the proerythroblast has been formed, it divides multiple times, eventually forming many mature RBCs. The first-generation cells are called basophil erythroblasts because they stain with basic dyes; the cell at this time has accumulated very little hemoglobin.