Table 2.

Zinc ion bioavailability, corticosterone, thymulin and TECs number and proliferation in young, old and very old mice

Mice	Thymulin activity (log-2)	AT/TT (log-2 (zinc ion bioavailability)	Corticosterone (ng/ml)	Plasma zinc (μg/dl)	% TECs	TECs proliferation (cpm)
Young	5.5 ± 0.5	1.1 ± 0.3	153 ± 18.3	110 ± 11	53 ± 11	750 ± 25
Old	1.07 ± 0.3*	3.0 ± 0.3**	265 ± 16.6**	80 ± 5.7++	21 ± 7**	227 ± 34**
Very old	2.5 ± 0.3+	1.0 ± 0.3	180 ± 12.4+	87 ± 43++	40 ± 12+	450 ± 39+

*p < 0.001 when compared to young mice; ⁺p < 0.05 when compared to old mice;

**p < 0.01 when compared to young and very old mice; ⁺⁺p < 0.01 when compared to young mice.