[The effect of Mitomycin C on the development of the male foreleg disk and on the formation of the bristle organ of Drosophila melanogaster after transplantation into host larvae].

1. Treatment of male foreleg disks ofDrosophila melanogaster with Mitomycin Cin vitro (Conc. 0,002-1 mg/ml) results in the formation of bristle organs without sockets after implantation into larval hosts. The formation of sockets without bristles was never observed. The capacity to form differentiated structures is also restricted after Mitomycin treatment. 2. Mitomycin C reduces the number of bracts, but the formation of hairs and claws is only affected after applying higher concentrations of the drug. It is postulated that the normal differentiation of the bract depends on the formation of a socket or an entire bristle organ. 3. When disks of different age were used, ranging from 72 hrs after egg deposition to 8 hrs old pupae, it was shown that the formation of bristle organs without socket is increased with increasing age. 4. There is no statistical difference between the use of 72 hrs and 96 hrs old host larvae with respect to bristle numbers and socket formation. The overall differentiation capacity seems, however, to be somewhat lower in young hosts. 5. The different parts of the leg are all affected to approximately the same degree. 6. The results are discussed with respect to possible mechanisms by which Mitomycin C might specifically influence socket formation and to problems, which arose from experiments using hosts and donors of different ages.