Table 2.

Low incidence of disease when arthritic IIJ mice were crossed with four other inbred strains^a

Crossb	Cage	F1	F2
AR × BALB/c	1	0 of 13	2 of 25
	2	0 of 18	0 of 19
AR × FVB	1	0 of 13	0 of 23
	2	1 of 22	2 of 38
AR × DBA1	1	0 of 20	0 of 21
	2	0 of 13	1 of 20
AR × C3H	1	1 of 16	0 of 24
	2	0 of 15	0 of 25

^aMice were followed for an average of 120 postnatal days and a minimum of 90 postnatal days, except in rare cases (< 2.5%) when males were killed earlier because of fighting with cagemates. ^bArthritic (AR) males from the IIJ strain were crossed with females from inbred strains. All arthritic F1 mice were used to generate the F2 generation.