Levels of gamma- and beta-globin mRNA in umbilical cord and adult blood reticulocytes. The copy number (× 1000) of cDNA for gamma-globin (A-B), beta-globin (C-D), and total (E,F; gamma + beta) in 440 individual reticulocytes collected from umbilical cord (CB) and adult (AB) are shown on each y-axis (Copy no.). Panels on the left (A,C,E) display data from 220 individual cells (x-axis) arranged from lowest to highest copy number. Panels on the right (B,D,F) show the mean copy number with standard deviations from each of the 5 cord blood donors (x-axis). Black bars indicates cord blood; open bars, adult blood; and gray bars, mean of 220 individual cells. AB indicates adult blood; CB, cord blood; and m, mean. Asterisks signify significance between cord and adult mean values (P < .005, paired Student t test).