EcollacZ^{βTub56D.β1WHI} reporter gene expression is first detected at late embryonic stage 13 in the abdomen in regions where the intersegmental apodemes will form. Expression extends rapidly during stage 14 and the apodemes are seen as continuous rows one cell wide. By stage 15, staining in three types of apodemes is seen ventrally, namely one intersegmental apodeme and two intrasegmental apodemes. Dorsally only the intersegmental apodemes are seen as consecutive lines of cells. Laterally, the attachment sites of pleural external muscles are stained.