Myoblasts from Drosophila wing disks can contribute to developing muscles throughout the fly

Abstract

In insect embryos groups of epidermal cells are already determined¹ to form particular compartments of the adult^2–4. In Drosophila this determination is maintained through cell divisions, is stable to experimental interference^1,5,6 and is thought to depend on the activity of a particular class of homoeotic genes^4,7,8. In contrast to our understanding of the ectoderm, we know little about determination of the mesoderm, which gives rise to the musculature. A recent study of cell lineage in the thorax of adult Drosophila has shown that the muscles of each segment are divided precisely into sets (P.A.L., in preparation). The dorsal and ventral muscle sets of the mesothorax probably derive from adepithelial myoblasts^9–11 in the wing and leg imaginal disk, respectively (P.A.L., in preparation). We describe here a new method of marking cells to trace myoblasts from the wing imaginal disk. We show that, when implanted, these mesodermal cells do not develop as they would in situ but instead contribute indiscriminately to developing host muscles. This result suggests that, whereas the ectodermal cells of the disk are committed to form a particular region of the adult, the mesodermal cells are not.