proeritroblasztból

Proerythroblast is the earliest recognizable precursor to the red blood cell in the bone marrow. It is a large nucleated cell, typically measuring 12-20 micrometers in diameter. The nucleus is round or oval, with fine, evenly dispersed chromatin and one or more prominent nucleoli. The cytoplasm is basophilic, meaning it stains blue with Wright's stain, due to the abundant free ribosomes that are actively synthesizing hemoglobin. Mitochondria are also present in the cytoplasm, although hemoglobin synthesis is the primary characteristic at this stage.

Proerythroblasts arise from hematopoietic stem cells and are committed to the erythroid lineage. They undergo a series of mitotic divisions and cytoplasmic maturation steps, progressing through the stages of basophilic erythroblast, polychromatophilic erythroblast, and orthochromatophilic erythroblast. During this process, the nucleus condenses and eventually is extruded from the cell, and the cytoplasm gradually becomes less basophilic and more eosinophilic as hemoglobin accumulates.

The proerythroblast stage is relatively short-lived, lasting only about 24 hours. Its primary function is to initiate the massive production of hemoglobin that will be contained within the mature red blood cell. The development of proerythroblasts is regulated by various growth factors, most notably erythropoietin, which is produced by the kidneys in response to hypoxia. Abnormalities in proerythroblast development or proliferation can lead to various forms of anemia or other hematological disorders.