Formation of Genetically Mosaic Mouse Embryos, and Early Development of "lethal (t12/t12)-normal" Mosaics.

The paper ?Formation of Genetically Mosaic Mouse Embryos and Early Development of Lethal (t12/t12)-Normal Mosaics,? by Beatrice Mintz [4], describes a technique to fuse two mouse [5] embryos into a single embryo. This work was published in the Journal of Experimental Zoology [6] in 1964. When two embryos are correctly joined before the 32-cell stage, the embryo will develop normally and exhibit a mosaic pattern of cells as an adult. Mosaics were easily characterized by mouse [5] fusions from embryos of different colors; this produced clearly visible color patterns identifying the alternate cell types. Mintz referred to the fused mice as mosaic or later as allophenic, but they are more commonly known today as chimeras [7].