The development of regional pigmentation patterns in black and tan (at) mice.

Mice which express the black and tan (at)allele at the agouti locus have black dorsal and yellow ventral hairs. To determine the site of action of this allele, the kind of hair pigment produced by various dermal-epidermal recombinations of dorsal and ventral black and tan (at/at), ventral nonagouti (a/a) and ventral yellow (Ay/a) embryonic skin has been investigated. The results indicate that it is the dermis which is responsible for the development of regional pigmentation patterns in black and tan mice.