Mosaic pattern and lineage analysis in chimeras.

Mammalian chimeras have been used in a number of developmental studies over the years. A major limitation in these studies has been the lack of in situ procedures for establishing mosaic pattern in the tissues of these animals. Recently, a number of procedures have become available for the histochemical demonstration of mosaicism in chimeras. These include the elucidation of various enzymes, receptors, or surface antigens, which have variant expression between strains. The observation of pattern in organs of mosaic animals can suggest possible modes of organogenesis and organ maintenance. Experimentation with such animals can be used to establish some mechanisms of pathogenesis as well.