Crinkly-tail, a mild skeletal mutant in the mouse

Crinkly-tail, cy, is a new recessive mutant with imperfect penetrance, in chromosome 4 of the mouse. The only abnormality is in the shape of the vertebrae for one, more rarely two, lengths of the region C9 to C14. This is expressed briefly in the 11-day-old embryo as a duplicated tail gut. None of the mechanisms operating in most of the 20 known tail mutants in the mouse operates in crinkly-tail. The defect is probably due to misallocation of the tissue derived from the primitive streak.