Table 1.

Fertility and incidence of anal atresia in TC/+ mice associated with genetic background

Genetic backgroundPercentage of successful matings*Total number of littersAverage litter size (average number of litters per pair)+/+ Offspring (% with anal atresia)TC/+ Offspring (% with anal atresia)P-value for χ2 analyses of Mendelian inheritance
C3.Cg-TC48.9386.2 (2.2)165 (0)73 (33.0)≤1 × 10−13
B6.C3(Cg)-TC45.8306.6 (2.7)117 (0)81 (19.8‡)≤0.001
STOCK-TC/JDown69.21418.1 (3.9)586 (0)557 (6.29§)0.26
  • The total live-born offspring recovered from TC/+X+/+ matings was used to determine expected values for ϰ2 analyses on each genetic background. For C3H.Cg-TC, B6.C3(Cg)-TC and STOCK-TC/JDown,ϰ 2=35.56, 6.55 and 0.74, respectively.

    8.33%, 75.0% and §28.5% of these also displayed hindlimb defects and a grossly shortened body.

  • * At least 24 breeding pairs of each background were paired continuously for 4 months. Failure to produce a litter within this window was classified as infertile.