[The coat color mutation in silver foxes (Vulpes vulpes): morphology of guard hairs]

The structure of guard hairs was analyzed in the mottling mutants of silver foxes. The mottling mutation occurred in the population of silver foxes which has been subjected to domestication. Hairs from the mottling areas were shown to have the following distinctions from silvery-black hairs: the lack of clear grana-shaft separation, a lesser thickness and length, another shape and pattern of guard-hair scales, another thickness ratio between cortical and medullar layers, a lesser number of melanocytes in hair bulbs, and a lesser number of dendritic processes in melanocytes. Putative mechanisms underlying the phenotypic effect of the mutant gene that controls mottling are suggested.