Genetical studies on the skeleton of the mouse XXIX. Pudgy

Abstract

The recessive mutant pudgy in the mouse has a greatly shortened vertebral column with highly irregular fusions between vertebrae and fragments of vertebrae. Ribs and sternum are also involved, but the rest of the skeleton is quite normal. The deformities arise from a defective segmentation. Although the paraxial mesoderm forms somite tissue with an epithelially arranged outer layer, this material either shows only an abortive segmentation into somites or, in the tail, none at all. A belated segmentation into dermomyotomes ultimately takes place, but the sclerotomic material remains continuous and gives rise to erratically abnormal blastemata which then chondrify and ultimately ossify.