Inbred strain documented F39. C3H/HeSnJ ash/ash mice were originally obtained from the Jackson Laboratory and subsequently bred at The National Cancer Institute, Frederick, MD, and the Roswell Park Cancer Institute. Mutant mice were maintained by breeding homozygous males with heterozygous females. The inbred nonagouti (a/a, ash/ash) ashen strain was generated by crossing C3H/HeSn-ash/ash mice to C57BL/6J mice. The F1 progeny were intercrossed and a/a, ash/ash mice were selected and intercrossed for 7 more generations. The a/a, ash/ash F8 mice were backcrossed once to C57BL/6J mice and the stock has been maintained by brother sister matings for 39 generations (F8N1F39).