抄録
The chromosomes of ten raccoon dogs from northern Honshu of Japan were examined by means of conventional and/or differential staining. The B chromo-somes were present in all of the specimens examined, showing marked intra-and interindividual variations in number. The modal number varied from individual to individual, and the intraindividual variation in diploid number was exclusively related to the number of B's, as confirmed by C-staining. Heterozygous Robertsonian fission of the pair No. 6 was detected in three of these ten specimens examined, one of which was a mosaic with non-fission and fission cell lineages, 2n=38+B's and 2n=39+B's. It was pointed out that the fission rearrangements of the Japanese raccoon dog were not necessarily specific to the central and southwest Honshu populations, but also detectable in the northern Honshu population, and the rearrangements from these localities including five cases reported so far were all heterozygous. The possible role of heterozygosity in the Japanese raccoon dog was briefly discussed.
