Abstract
Enzyme marker techniques allow the identification of the genotype of internal tissues in
Drosophila genetic mosaics. These methods were used to derive fate maps for the nervous system and several other internal organs. The fate maps were compared to other cell lineage studies and to the fate mapping results on neurological mutants. The mosaic data for the nervous system also indicate that only a few blastoderm cells (3–10) give rise to each major ganglion.