Fig. 8

Caudal and Wnt gene expression maps directly to boundaries of EdU domains. Posterior of larvae showing both in situ expression domains and EdU incorporation. In each case, anterior is left and the posterior edge of the EdU band (red arrowhead) is denoted. a Cad expression extends throughout the entire growth zone and borders the telson, overlapping the posterior Wnt4 and WntA expression. b Posterior WntA expression is mainly in the anterior growth zone, where there are very few to noEdU positive cells. The anterior border of cad (a) and WntA (b) both flank the posterior edge of the synchronized EdU band in the newest specified segment. c Posterior Wnt4 expression excludes the band with rare EdU staining and overlaps with the unsynchronized EdU region in the posterior growth zone. Wnt4 also appears to have a concentration gradient from posterior border towards anterior border. The anterior border of Wnt4 expression meets the posterior border of WntA expression. d Wnt6 is expressed in the telson and e in the cells that form the apical ridge of the limb buds, which also show EdU expression (white arrows)