Analysis of mandible of newly developing strain of Japanese white rabbit (Nib:JWNS).

In the present paper, we applied analysis of the mandible to a new strain of Japanese White rabbit being developed (Nib: JWNS), at 5th and 8th generations (F5 and F8), and evaluated the process of establishment, making comparison with the parent colonies (I, K and L), and other established JW colonies (A, E, O and R). The mandibles were measured at 12 sites and the data obtained were calculated by principal component analysis and discriminant analysis. As a result of principal component analysis, the parent colonies were found to be close to one another with intermediate size of the mandible and height of condyloid and angular processes, but in F5 and F8 the mandibles were slightly shorter in height and different from those in the parent colonies. On the other hand, results of discriminant analysis revealed that mandibles were discriminated correctly 100% in colonies A, O and R, and 90% in E and I. Colonies A, O, R, E and I were therefore regarded as established strains. In the developing colonies, the discriminant rate was 70% in F5 and 80% in F8. One mandible from F5 and two from F8 were wrongly classified to the parent colony L, which was the lowest discriminant rate among the colonies examined (61.5%). The results of both statistical analyses suggest that the JWNS are almost established at 8th generation as a new strain.