Figure 1

Rat life cycle study design and animal body weight growth curves. Untreated male and female F344 rats (A.) were sacrificed at 2, 5, 6, 8, 15, 21 weeks (male and female n = 6 per age group), 52 weeks (males n = 10, female n = 10), 78 weeks (male n = 8, female n = 8) and 104 weeks (male n = 6, female n = 16) of age corresponding to essential life stages (B.) during animal growth and maturation. Liver tissues were collected and used for whole rat genome expression profiling (n = 5 per sex, per age group). Animal body weights (n = 6 to 16, +/-SEM) were recorded at necropsy. Two week old animals were not weighed to decrease handling stress. Rapid growth during early development subsides after 15 weeks and males reach nearly twice the weight of females at 52 weeks.