Table 1.

Testing of female fertility

Female genotype	n	Litters	Pups	Litters per female	Pups per litter
+/+	6	17	150	2.8 ± 0.4	8.8 ± 2.5
−/−	11	19	59	1.7 ± 1.0*	3.1 ± 1.8**

Results are presented as mean ± SD. ∗, P < 0.05 vs. +/+, Student’s two-tailed t-test. ∗∗, P < 0.001 vs. +/+, Student’s two-tailed t-test.