Table 1.

Frequencies of HSCs in the BM of young and aged B6-CD45.1 and D2-CD45.1

Cells injected	Unseparated BM		Lin−
	HSC frequency*	No.†	HSC frequency*	No.†
D2 young	24.7 (16.3-37.3)	4	226.1 (136.7-373)	3
B6 young	8.3 (5.4-12.7)	5	100.6 (75-133.6)	7
D2 aged	ND		248 (160-384.4)	3
B6 aged	11.3 (7.2-17.8)	3	152.7 (77.6-300.4)	1

^*Frequency of HSCs per 100 000 cells injected; the 95% confidence interval is given in parentheses.

^†No. indicates number of experiments. For each experiment 10 to 20 hosts were injected per cell dose. Data from experiments within a group were combined to calculate the frequency.