The mammalian spot test (Fellfleckentest) with mice

Abstract

Embryos from the cross C57BL/6JHan x T which are heterozygous among other for 4 recessive coat-color genes were treated in utero by injection of a mutagen into the peritoneal cavity of the mother animal. If this treatment did lead in a pigment precursor cell to an alteration of the wild type allele of one of the four genes under study or to its loss, a brownish or light to dark gray color spot in the adult black coat could be seen. White midventral spots which also occur are predominantly the result of pigment cell killing, while the nonwhite spots with perhaps the exception of the white-gray should be the result of either gene mutations or recombinational processes. Of the numerical and structural chromosome aberrations produced only the few come into consideration which are able to pass the filter of several mitoses.