Cell Death During the Development of the Imaginal Disks of Calliphora Erythrocephala

1. During the third instar and the prepupal period many degenerating cells are found in the imaginal disks of Calliphora. They can be easily demonstrated in whole disk preparations with the help of any of several basic vital dyes. 2. The degenerating cells become visible ca. 8-10 hours after the onset of cell death and are resorbed within a period of 24 hours. 3. A strong acid phosphatase activity was found to be present in degenerating cells in an early stage of disintegration. 4. The degenerating cells show a very characteristic localization for each disk. The pattern of cell death was described both qualitatively and quantitatively. In the early third instar the localization of the degenerating cells within the pattern is rather variable, but it becomes more constant during development. 5. In the wing disk of the wild type of Drosophila hydei and D. melanogaster a pattern is found that is similar to that in the wing of Calliphora. In so far as it was examined the pattern in the other disks agrees with that of the corresponding disks of Calliphora. 6. In the wing disk of three mutants of Drosophila (beaded, xasta, and vestigial) the pattern of cell death could be related with the missing parts of the adult wing. 7. As judged by its localization the cell death observed probably has a morphogenetic significance. This is discussed with the help of a model.

Affiliations: 1: ( Zoological Laboratory, University of Leiden, The Netherlands