Histotypic reaggregation of dissociated imaginal disc cells ofDrosophila melanogaster culturedin vivo

Developmental parameters of cell death in the wing disc of Drosophila

Apoptotic cell death in wing imaginal discs takes place in single cells or small clusters of neighboring cells. These cells are distributed throughout the anlage at early stages and in recognizable territories at late larval and pupal stages. Apoptotic cells remain in the epithelium 2-4 h, prior to being engulfed in place by hemolymph cells. Experimentally induced apoptosis in single cells or territories is accompanied by nonautonomous death of adjacent cells and of cells further away in adjacent territories. These effects are followed by changes in cell proliferation in both territories. Apogenetic mosaics in mutant discs show cell death throughout the anlage. Apoptosis provides a mechanism, in addition to cell proliferation control, for matching territories with different positional values or different genetic specifications.

Cell lines from imaginal discs of Drosophila melanogaster

New cell lines, designated as ML-DmD1-10, were established from dissociated imaginal discs of Drosophila melanogaster. The culture medium was prepared by mixing in a 1:1 ratio Cross and Sang's M3(BF) medium, supplemented with 10% heat inactivated fetal bovine serum (FBS), with the supernatant of a primary embryonic cell culture made in the M3(BF) medium and supplementing this mixture with insulin. One cell line was established in the medium containing larval hemolymph instead of the primary culture supernatant, and another was established in fresh M3(BF) medium supplemented with insulin and FBS. In these mediums, imaginal disc cells first formed aggregates and cellular vesicles within a few weeks followed by the proliferation of thin-layered cells around them after about 1 mo. Ten cell lines have so far been established from two kinds of imaginal discs and disc mixtures. The ploidy of these cell lines was predominantly diploid. Population doubling time was about 50 to 70 h at 3 to 10 mo. after initiation of the culture. When the cell aggregates formed in vitro were implanted in metamorphosing larvae, they differentiated at high frequency into adult cuticular structures in the early phase of the primary culture. This differentiation of aggregates was also observed, though at low frequency, in a culture maintained by dilution-transfer for 6 to 15 mo. in vitro.

Dissociation and sorting out of Drosophila imaginal disc cells

Previous attempts to study sorting out of Drosophila imaginal disc cells have been hampered by an inability to thoroughly dissociate these cells and the need to use cuticular markers which require several days of in vivo culture. This study overcomes these limitations by using a new dissociation procedure and a genetic marker for undifferentiated cells, the succinate dehydrogenase8 (sdh8) mutation. Dissociated and reaggregated cells from wing and leg imaginal discs segregated or "sorted out" from one another after only 24 hr of in vivo culture. It was also found that leg cells from different body segments may sort out, but to a lesser degree than wing and leg cells. Mixtures of wing and haltere cells did not sort out, in contrast to previous reports. These results constitute the first unambiguous study of sorting out with Drosophila imaginal disc cells and indicate that dorsally situated imaginal cells share a recognition specificity which is different from that of ventral imaginal cells.