The technique developed by Hadorn in which an imaginal disc is removed from a mature Drosophila larva, cut in half, and the half organ implanted into a young larva. Here regenerative growth occurs, and once the host larva has reached maturity the implant is removed once again, bisected, and one of the halves transplanted to a new host. By multiple repetition of this procedure, the cells are subjected to an abnormally long period of division and growth in a larval environment. If the regenerated disc is finally allowed to undergo metamorphosis, it shows an abnormally high probability of producing structures characteristic of different discs. A regenerated genital disc may produce antennae, for example. Hadorn terms such differentiation allotypic. Since the allotypic organs appear in the offspring of cells that were previously determined to form genital structures, a change in determination must be postulated. This event is called transdetermination. See Chronology, 1963, Hadorn.
Subjects: Genetics and Genomics.