proeritroblast

The proerythroblast, also known as the pronormoblast, is the earliest recognizable precursor to the red blood cell in the bone marrow. It originates from the hematopoietic stem cell lineage. Morphologically, the proerythroblast is a large cell, typically 12-20 micrometers in diameter. It possesses a large, round or oval nucleus that occupies a significant portion of the cell volume. The chromatin within the nucleus is fine and lacy, and nucleoli are usually visible. The cytoplasm is basophilic, meaning it stains blue due to the presence of abundant ribosomes involved in protein synthesis, specifically hemoglobin.

The proerythroblast undergoes several mitotic divisions to produce a population of more mature erythroblasts. During this process, the nucleus gradually condenses and becomes smaller, and the cytoplasm changes from basophilic to eosinophilic, indicating the increasing accumulation of hemoglobin. The cell size also decreases with each division. The proerythroblast is a critical stage in erythropoiesis, the process by which red blood cells are produced. Its presence and morphology are important indicators in hematological diagnostics, as abnormalities can suggest various types of anemia or other bone marrow disorders.