Fate map and cell lineage relationships of thoracic and abdominal mesodermal anlagen in Drosophila melanogaster.

We have examined the cell lineage of larval and imaginal precursors of the mesodermal anlage between 10% and 60% egg length (EL) by homotopic single-cell transplantations at the blastoderm stage. Clones in the larval somatic muscles and in the fat body were derived from transplantations everywhere between 10% and 60% EL along the ventral side of the embryo. Clones frequently overlap these tissues and can extend over a maximum of four segments in the larval somatic muscles or over two morphologically-distinct parts in the fat body. Clones in the gonadal mesoderm overlap with other mesodermal derivatives and exhibit different mitotic behaviour in the two sexes. We present a blastoderm fate map for the fat body, the larval somatic muscles and the gonadal mesoderm. Clones in the imaginal muscle precursors of the abdomen, as well as of the thorax, always show a common cell lineage with larval somatic muscles and partly with other mesodermal tissues. These clones of imaginal derivatives are always found within a single segment, while the overlapping clone parts in the larval somatic muscles can label up to three segments.