TABLE 3.

Analysis of the erythroid subpopulations in E15.5 and E16.5 wt and Prep1^i/i fetal liver cells^a

Stage	No. of embryos	Genotype(s)	% Erythroid differentiation for subpopulationb:				Total no. of FL cells (106)
			R1	R2	R3	R4
E15.5	13	+/+, +/i	3.48 ± 0.56	3.8 ± 1.15	54.7 ± 5.44	32.5 ± 4.18	46.3 ± 9.73
E15.5	10	i/i	3.15 ± 0.63	5.1 ± 1.9	59.1 ± 6.1	27.9 ± 4.8	33.1 ± 5.3
E16.5	6	+/+, +/i	4.6 ± 2.2	2.19 ± 0.9	45.1 ± 24.3	42.2 ± 24.7	71.6 ± 7.4
E16.5	1	i/i	96.2	0.02	0	0.19	30.0
E16.5	1	i/i	44.9	1.2	2.6	43.3	4.0
E16.5	1	i/i	4.9	1.74	9.2	79.5	57.0

^aThe table shows the data averaged from three E15.5 litters and from a single E16.5 litter generated by crossing Prep1 heterozygous mice. The mean values and standard deviations are shown for the E15.5 embryos, while only the wt and heterozygous embryos are averaged for the E16.5 embryos. For E16.5 Prep1^i/i embryos, the data for each individual are shown. For this reason, no P values are shown for the E16.5 embryos. However, it is evident that 2 of 3 Prep1^i/i embryos show enrichment in the least differentiated R1 subpopulation. P values: R1, 0.1; R2, 0.029; R3, 0.04; R4, 0.012; total, 0.00045.

^bErythroid differentiation was monitored by measuring the expression of CD71 and Ter119 by flow cytometry. The various subpopulations are classified as follows: R1 (CD71^med-Ter119^−/lo), earliest progenitors; R2 (CD71^hi-Ter119^−/lo), proerythroblasts and early basophilic erythroblasts; R3 (CD71^hi-Ter119^hi), early and late basophilic erythroblasts; R4 (CD71^med-Ter119^hi), chromatophilic and orthochromatic erythroblasts (57).