Table 1.

The number of cells in spleen, bone marrow, and thymus from 6~8-week-old or 24-month-old mice.

	Young	Aged
Spleen	2.3 × 107 ± 0.8	3.2 × 107 ± 0.6
Bone-marrow a)	2.0 × 107 ± 0.3	2.1 × 107 ± 0.6
Thymus	5.1 × 107 ± 2.9	1.3 × 107 ± 0.2

Each value represents mean ± S.D. for three mice.

^a) Bone-marrow cells were collected from both femurs.