Sparse coat (spa) arose spontaneously in the jagged tail (jg) buff (Vps33abf) stock (JGBF/LeJ Stock No. 000260) at F3 in 1966 at The Jackson Laboratory. The first sparse coat female was mated back to her father and a sparse coat male offspring was then outcrossed to a B6CBACAF1/J Aw-J/A female. The stock was then sibling mated to F8 and again crossed to B6CBACAF1/J Aw-J/A. It was continually mated to the hybrid by the cross-intercross system and was cryopreserved in 1987 by mating homozygous sparse coat males at N34F1 to B6CBACAF1/J Aw-J/A females.