Differential morphophysiological characteristics of erythrocyte precursors and mature erythroid cells in early postnatal ontogenesis of birds

In accordance with the recommendations of The International Council for Standardization in Haematology (ICSH, https://icsh.org/), this article describes the morphophysiological characteristics of the precursors and mature erythroid cells in the early period of postnatal development of birds (Gallus gallus L.) including calculation of the surface area of these cells (S, μm2 , X±SEM). Depending on cell shape, cytoplasm color, and chromatin organization in nucleus, the following types are distinguished: basophilic erythroblasts (69.60±4.01 μm2 , p≤0.05), polychromatophilic erythroblasts (65.42±2.49 μm2 , p≤0.05), and oxyphilic erythroblasts (71.10±4.43 μm2). Formation of cell pool is characteristic for erythropoiesis in birds due to mitotic proliferation of basophilic erythroblasts. There are often proerythroblasts and polychromatophilic erythroblasts. The nucleus of a polychromatophilic proerythroblast contains a large number of histone proteins; therefore, it has an intensely basophilic color with a pronounced oxyphilic hue (proteinrelated oxyphilia). The accumulation of hemoglobin in the protoplasm of these cells contributes to the gradual transition of the basophilic staining of cytoplasm to the oxyphilic one which is typical for mature red blood cells (73.95±2.10 μm2 , p≤0.05). Cell shape and the structure of erythroblast nucleus approaches to these of mature red blood cells.