[Congenital malformation of the skeleton in Weiser-Maples guinea pigs].

Some abnormalities were observed in the occipital bone, cervical vertebrae and thoracic vertebrae of Weiser-Maples guinea pigs. In the occipital bone, the medial basilar impression was suggested to occur in 40 (32.8%) out of 122 animals. The basilar impression was classified into right, left and both side types and observed in 24, 11 and 5 animals, respectively. The basilar impression was known to be accompanied in human with some anomalies such as platybasia, Klippel-Feil syndrome, deformation of foramen magnum and so-on. These anomalies were also observed in guinea pigs. The fusion of the axis with the 3rd cervical vertebra was observed in 12 (10.5%) out of 114 animals. The deformation was sometimes observed in the temporal, interparietal, atlas and axis as well as the occipital bone. The fusion of the 7th cervical vertebra with the 1st thoracic vertebra was found in 46 (51.7%) out of 89 animals. This fusion was thought to have no relation with the basilar impression. Weiser-Maples guinea pigs are now in 19 generations of sibmating. Because these abnormalities as mentioned above are all thought to be inherited, the selective breeding will make Weiser-Maples guinea pigs suitable for the study of the basilar impression.