Hybrid Cell

A heterokaryon, with two separate nuclei, eventually proceeds to mitosis. This produces a hybrid cell in which the two nuclear envelopes have been disassembled, allowing all the chromosomes to be brought together in a single large nucleus. Although such hybrid cells can be cloned to produce hybrid cell lines, the initial hybrid cells are unstable and lose chromosomes. For unknown reasons, mouse-human hybrid cells predominantly lose human chromosomes. The loss is random and gives rise to a variety of hybrid cell lines, each of which contains only one or a few human chromosomes. This phenomenon has been used in mapping the locations of genes in the human genome.