Functional morphology of blood erythroid cells in Neogobius melanostomus P. during cell differentiation

The morphometric characteristics of the following immature erythroid cells in circulating blood of the round goby ( Neogobius melanostomus P.) were studied: late basophilic normoblasts (BN), polychromatic normoblasts (PN): normocytes (mature erythrocytes). The linear dimensions of the blood cells were evaluated on photographs in a computer program ImageJ 1.44p. The longitudinal and transverse axes of the cell and its nucleus were measured. Using appropriate algorithms, the following parameters were calculated: shape index ( SI ), volume ( V c ), area ( S c ), thickness ( h ), and specific surface area ( SS c ) of cells and nuclei as well as the nuclear–cytoplasmic ratio ( NCR ). Major changes were found to occur at the stage of PN → normocytes, being aimed at improving the respiratory characteristics of cells. In addition to accumulating hemoglobin in the cytoplasm and suppressing functional activity of the nucleus, a significant increment in the diffusion surface of erythroid cells was noted. As compared to BNs, S c and SS c of normocytes increased by 40 and 17%, respectively, while the cells assumed an ellipsoid shape. The processes underlying the formation of the mature erythrocyte cytoskeleton are discussed.