A sequential staining technique for karyotypic analysis of interspecific somatic cell hybrids

We describe a sequential staining technique for the karyotypic analysis of interspecific mouse X human somatic cell hybrids. Fluorescence in situ hybridization of samples, previously stained using standard trypsin/Giemsa protocols, was instrumental in the identification of human chromosomes present in hybrid lines. This procedure not only provided a simple distinction between human and mouse chromosomes, but it also allowed the visualization and monitoring of human sequences present in interspecific translocations and subchromosomal fragments.