Midfacial retrusion in adult brachyrrhine mice.

The purpose of this study was to determine quantitatively whether the Br mouse displays craniofacial size and shape patterns indicative of midfacial retrusion. Fifteen craniometric variables derived from a total of 40 male and female Br mice were compared with an equivalent number of C3H/HeJ adult mice displaying normal murine craniofacial morphology. Univariate statistical analysis showed that Br crania were significantly smaller for all measurements as compared with the C3H/HeJ specimens. Multivariate analysis revealed that the pattern of measurement covariation differed significantly between the two samples. Results indicated that the midface was significantly shorter in length relative to the calvaria in mutant mice was compared with C3H/HeJ mice. Therefore, the sagittal midfacial growth trajectory is deficient in Br mice.