Table 1.

Distribution of clonogenic cells in sorted SCL^lacZ/w bone marrow fractions

Genotype* (n)	Stimulus†	Colony type	Progenitor yield‡		Colony distribution, %§
			Unsorted	Sorted	lacZneg	lacZint	lacZhigh
Agar cultures
SCLlacZ/w	IL-3	Day 7 myeloid	59  ± 11	102  ± 32	5  ± 4	64  ± 22	31  ± 26
(5)	SCF	Day 7 myeloid	42  ± 6	69  ± 25	8  ± 12	63  ± 14	29  ± 23
SCLw/w	IL-3	Day 7 myeloid	63	76	95	5	NA¶
(2)	SCF	Day 7 myeloid	47	53	95	5	NA
Methylcellulose cultures
SCLlacZ/w	Epo	Day 2 CFU-E	189  ± 20	70  ± 43	0.3  ± 0.5	16  ± 14	84  ± 14
(3)	Epo/IL-3	Day 7 BFU-E	13  ± 11	18  ± 7	0.6  ± 1	50  ± 22	49  ± 22
		Day 7 myeloid	34  ± 12	60  ± 21	10  ± 5	60  ± 19	30  ± 17

^*Bone marrow cells from mice of the indicated genotype were cultured in duplicate in agar or methylcellulose in the presence of growth factors for 2 or 7 days and the colonies counted. The number of experiments is shown in parentheses. 

^†IL-3 was used at 1,000 units/ml, SCF at 100 ng/ml, and Epo at 4 units/ml. 

^‡The number of CFCs in cultures of 2.5 × 10⁴ bone marrow cells (unsorted) compared with the calculated recovery of CFCs from the sorted fractions. This figure was calculated for each experiment by summing (progenitor frequency × % of cells) for each fraction and then determining the mean for each group of experiments. Values given represent the mean ± SD. The mean progenitor frequency and the mean % cells in each fraction are shown in Fig. 3. 

^§The distribution of CFCs in the sorted bone marrow fractions given as a percentage. 

^¶NA, not applicable, since all lacZ-positive SCL^w/w bone marrow cells were lacZ^int.