(a) TPOAb develop in male and female parental NOD.H2h4 and some F2 and N2 pups, but not in parental BALB/c or F1 mice. Data are shown for individual male and female mice; the numbers of mice in each group are provided in parentheses. The shaded area represents the mean ±2 standard deviations for values in BALB/c mice. Significant differences between males and females: F2, ^P = 0.01 (Mann–Whitney U statistic); N2, *P = 0.004 (Mann–Whitney U statistic). #TPOAb were measured in F2 offspring that were homozygous or heterozygous for the NOD.H2h4 MHC haplotype (kk or kd). (b) Thyroiditis in male and female parental NOD.H2h4, BALB/c, F1, and N2 pups. Thyroiditis was not determined in F2 offspring. Data are shown for individual mice. The numbers of mice in each group are provided in parentheses. The value 1 was assigned to thyroid glands with no infiltration. Geo, geometric.