Ecol\lacZsvp-AE127 is expressed in seven segmentally repeated pairs of ostial cardioblasts.
Expression is observed in heart progenitors from embryonic stage 11. It is first observed in at least two cells per hemisegment in the posterior half of the embryo. From stage 12, expression observed in 4 strongly-expressing cardioblasts are seen in seven posterior segments in the embryo, with an additional pair of cells situated caudally to these and the pattern is maintained in stages 13-15. In stage 15, strong expression is observed in two adjacent pairs of cardioblasts in seven segments, plus another single pair located immediately poasterior to the last double pair of cardioblasts. The svp pattern is complementary to the tin pattern in that the two pairs of svp-expressing cardioblasts do not express tin. Expression is also observed at the anterior end of the dorsal vessel in cells that will become the corpus allatum and weakly in some pericardial cells.