Does the T-locus in the mouse include ribosomal DNA?

The proportion of rDNA in the mouse genome is shown to have no systematic relation to the T-locus genotype, and hybridization in situ with 125I-RNA does not label chromosome 17, which carries the T-locus. Thus rDNA need no longer be taken into account in explaining the unique properties of the alleles at this locus. The number of genes for rRNA precursor averaged 153 per haploid genome, but a large measure of individual variation is suggested.