Abstract
To determine the manner in which erythrocyte changes occur during ontogeny, several red cell parameters were analyzed in 19 fetuses, 14 newborn infants, 19 children and 45 adults. Although MCV and Hb F levels decreased as expected during in utero development, the coefficient of variation of red cell size (%CV = SD/mean), or red cell distribution width (RDW), increased from fetuses to newborn infants, and then decreased in children to adult levels. In normal children and adults, in which erythropoiesis was in steady-state, the %CV was 15 (RDW was 13). The %CV in fetuses at 18 to 24 weeks gestation was 18, and it was 21 at term birth. This high value for %CV in newborn infants indicates substantial anisocytosis. Erythropoiesis at the time of birth is not a steady-state condition. Erythrocytes of a wide variety of sizes are present, with the appearance of new small cells on a background of older, larger red cells. This increased anisocytosis suggests that these new erythrocytes do not appear due to a smooth, continuous evolution of red cell size, but due to discrete, perhaps clonal changes.
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Alter, B., Goldberg, J. & Berkowitz, R. RED CELL SIZE HETEROGENEITY DURING ONDOGENY. Pediatr Res 21 (Suppl 4), 296 (1987). https://doi.org/10.1203/00006450-198704010-00772
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DOI: https://doi.org/10.1203/00006450-198704010-00772