A comparative study of the coats of chimaeric mice and those of heterozygotes for X-linked genes

Abstract

SUMMARY: The coats of Ta–Ta⁺ and c–c⁺ chimaeric mice have been compared with those of Ta heterozygotes and animals heterozygous for an X-autosome translocation which causes c-variegation. With one exception all those features typical of the heterozygotes were found in their chimaeric counterparts, thus showing that the creation of two cell populations by X-inactivation can ultimately lead to the observed heterozygous phenotypes. The one exceptional feature not found in c-variegated chimaeric mice was the progessive increase in the proportion of pigmented hairs in c areas with age which occurs in X-autosome translocation heterozygotes.The coat of a Mo^dp / + – Ta chimaeric animal was also investigated. Ta hairs showing only the colour effect of Mo^dp were numerous, suggesting that Mo^dp and Ta affect different cell populations. However, Ta hairs showing the structural effect of Mo^dp were very rare. The two observations suggest Mo^dp can operate independently upon two different cell types – melanocytes and hair follicle cells.