ABSTRACT
The hair interior defect mutation arose spontaneously on the AKR strain. It was first recognized in AKR mice obtained from the M.R.C. Laboratory Animal Care Center in Carhalton and later in AKR mice from the Imperial Cancer Research Fund, Mill Hill, Great Britain, and from the Jackson Laboratory in Bar Harbor, Maine. The hair interior defect mutation has been shown to be a recessive mutation, but it has not been mapped. The morphology of the medullary cells, corticomedullary junction, and width of the hair shafts are abnormal. The abnormal development of the medullary cells can be seen in histologic sections of skin and hair follicles to begin just above the matrix of the bulb. The hair cycle proceeds normally in hair interior defect mutant mice. The hair interior defect mutation is a feature of all AKR/J mice. These mice are readily available from the Jackson Laboratory Animal Resource.
