Figure 1.
Highly significant differences in gestation length among inbred mouse strains.
(A) Gestational length presented in total hours, measured from the midpoint of the dark cycle prior to the appearance of a copulation plug to the recorded appearance of the first pup. The total number of pregnancies monitored is indicated for each strain and data are presented as the mean +/− S.E.M. A detailed description of the animal husbandry and measurement procedures is provided in the supplementary methods (6). (B) Live litter size (number of pups), maternal weight gain (at E14.5) and maternal load (% weight gain) for each of the 15 inbred strains measured in (A). Complete data are presented in Table 1. (C) Effects test (analysis of covariance) demonstrating significant differences in GL among inbred strains independent of the effect of total litter size and maternal load. Litter size is also significantly different among strains and is strongly correlated with GL. (D) Graphical representation of strains with significantly different GLs independent of all other factors. Strains that are not associated by a letter are significantly different from each other (p<0.05).
Table 1.
Data summary from individual strain measurements.
Figure 2.
Gestation length is primarily dependent upon maternal genotype.
(A) Gestation length presented in hours of C57BL/6J, A/J, B6.CB17-Prkdcscid/SzJ (B6-scid), and B6-scid with transplanted A/J ovaries (AJ-ov-B6-scid). In order to directly compare the effect of pure B6 and A/J pups in a B6 maternal background, B6-scid mice were sham manipulated and mated to B6-scid males, while AJ-ov-B6-scid females were mated to A/J males following recovery from ovary transplant (see materials and methods for details). (B) Graphical representation of strains with significantly different GLs independent of all other factors. Strains that are not associated by a letter are significantly different from each other (p<0.05), demonstrating that B6 females show no statistical difference in gestation time, regardless of the genotype of the pups.
Figure 3.
Complex, polygenic regulation of gestation length is revealed by the B.A CSS panel.
(A) Mean gestation time in total hours for each of 20 CSS. The total number of pregnancies monitored is indicated for each strain and data are presented as the mean +/− S.E.M. (B) Graphical representation of individual CSS with significantly different GLs independent of all other factors. Strains that are not associated by a letter are significantly different from each other (p<0.05).