Development of rib-vertebrae: a new mutation in the house mouse with accessory caudal duplications.

The new recessive mutation rib-vertebrae (rv) causes fusions of lower ribs and malformations of vertebrae, which results from disturbed somite arrangement. In addition, duplications of the caudal neural tube and sometimes unilateral suppression of kidney formation can be observed. The new mutation is compared with the six already known mutations in mice with "Wirbel-Rippen-Syndrome" and with a similar syndrome in man. From the various effects of the rv-gene observed, it is suggested that the gene causes abnormal inner and outer surface formation, producing manifold secondary effects.