Table 1.

Incidence and multiplicity of papilloma in the parental strains, F1 and F1 backcross

Strain		Animal No.	Incidence (%)	Multiplicity a)
FVB/N	total	16	16 (100)	32.56 ± 3.60
	female	9	9 (100)	28.22 ± 4.46
	male	7	7 (100)	38.14 ± 5.36
PWK/Rbrc	total	10	0 (0)	0
	female	10	0 (0)	0
	male	10	0 (0)	0
FVB × PWK	total	25	4 (16)	0.32 ± 0.8
	female	14	4 (28.6)	0.57 ± 1.01
	male	11	0 (0)	0
PWK × FVB	total	17	0 (0)	0
	female	8	0 (0)	0
	male	9	0 (0)	0
(FxP) × F	total	208	123(56.7)	4.86 ± 0.56
	female	107	60(56.1)	3.45 ± 0.64
	male	101	63(62.4)	6.34 ± 0.92

^a) data are shown as mean ± SEM.