Table 2.

Fecundity of the Tnp1-mutant males during an 8-week mating period

Background  (age at start of mating)	Tnp1 genotype	Fraction fertile, fertile/total	Litters per fertile pair, n	Mean litter size, n
B6 × 129 F2 (16 weeks)	+/+	10 /10**	2.6  ± 0.2*	6.6  ± 0.4
	+/−	10 /10**	2.1  ± 0.2	5.8  ± 0.5
	−/−	3 /10	1.7  ± 0.3	7.2  ± 1.2
129 (9 weeks)	+/+	9 /10*	2.4  ± 0.2*	7.7  ± 0.3**
	+/−	10 /10**	2.0  ± 0.1	7.5  ± 0.5**
	−/−	4 /10	1.5  ± 0.3	1.6  ± 0.5

Values are significantly higher than those from Tnp1−/− (χ² for fertility; Student's t test for other endpoints). *, P < 0.05; **, P < 0.005.