title: Red cell size heterogeneity during ontogeny.
abstract: To determine the manner in which erythrocyte changes occur during ontogeny, several red cell parameters were analyzed in fetuses, newborn infants, children, and adults. Although mean cell volume (MCV) and hemoglobin F (HbF) levels decreased as expected during in utero development, the coefficient of variation of red cell size (%CV), or red cell distribution width (RDW), increased from fetuses to newborn infants. In normal adults, the %CV was 15 (RDW was 13). The %CV in fetuses at 18-24 weeks gestation was 18, and it was 21 at term birth. High values for %CV or RDW indicate significant 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 to be due to a smooth, continuous evolution of red cell size, but rather to discrete, perhaps clonal, changes.
authors.affiliation: Polly Annenberg Levee Hematology Center, Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029.
authors.forename: B P
authors.initials: BP
authors.lastname: Alter
authors.forename: J D
authors.initials: JD
authors.lastname: Goldberg
authors.forename: R L
authors.initials: RL
authors.lastname: Berkowitz
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D004909:Erythrocyte Indices; D004920:Erythropoiesis; D005260:Female; D005312:Fetal Blood / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male
chemical_list: D006454:Hemoglobins