EcollacZ reporter gene expression isobserved from embryonic stage 13. The pattern closely resembles labexpression in a thin stripe of cells in the midgut epithelium thatcoextends approximately with Ubx expression in parasegment 7 of theadhering visceral mesoderm. The stripe widens and displays a gradedpattern with the strongest expression posteriorly. As with labexpression, a 2-3 cell wide gap is present between the posterior boundaryof EcollacZ expression and the second midgut constriction. No expression isobserved elsewhere in the embryo. In lab mutants, midgut expression iseliminated prior to stage 15 and occurs at low levels thereafter.Expression is completely eliminated in dpp mutant embryos.