Fig. 6. abd-A expression induces an increase in Svp cell size in the aorta. Shown are the mean sizes (in µm) of the svp-expressing dorsal vessel cells of control y w embryos, and embryos in which abd-A is expressed throughout the mesoderm. S1 to S7 represent the segmentally repeating groups of Svp cells, from anterior to posterior. Error bars represent standard errors of the mean. Note that in y w the Svp cells that form the ostia (S5-S7) are larger than those in the aorta (S1-S4). Upon induction of ectopic heart, all Svp cells assume a larger average size.