Chimeric mice containing a human chromosome were produced by introducing a human chromosome into mouse embryonic stem cells via microcell-mediated chromosome transfer.
In present study, the dead foetuses of the chimeric mice containing a human chromosome 2-derived fragment (hChr.2f) or a human chromosome 21 (hChr.21) were studied anatomically in order to examine the effects of introduction of a human chromosome to mouse. Polydactyly were obsered in almost of the chimeric foetuses containing hChr.2f, but were not detected in the chimeric foetuses containing hChr.21. Aplasia of the sternum and delayed ossification or deletion of the cervical vertebrae centrum were universally observed in both the chimericfoetuses. Histological abnormalities in heart and liver were frequently detected in both the chimeric foetuses. Interestingly, the number of germ cells decreased remarkably in all of the chimeric foetuses containing hChr.21.