FIG. 10.
dys fusion cell expression requires esg function in some tracheal branches. Anterior is to the left. Arrowheads indicate fusion cells. Fusion cell gene expression was examined in esgG66 mutant embryos, which express esg-lacZ. Stage 15 embryos were stained with α-β-Gal and α-Dys. Merge images are shown on the left. The dorsal branch (DB) has esg-lacZ-positive fusion cells, but there is no Dys protein present. The dorsal trunk (DT) fusion cells express both esg-lacZ and dys. Occasionally, esgG66 mutant embryos had a reduced number of dorsal trunk fusion cells. The ganglionic branch (GB) has esg-lacZ-positive fusion cells, but Dys protein is absent. Most lateral trunk (LT) fusion cells are absent due to cell death (42), and there are no esg-lacZ or Dys-positive cells present. The arrows indicate sites in which fusion cells are located in wild-type lateral trunks. esg-lacZ-positive cells that are not fusion cells are indicated by an asterisk.