Fig. 6. Model of the ecdysone-dependent control of cardiac tube remodelling during metamorphosis. Ecdysone signalling triggers adult heart formation throughout the transcriptional regulation of Ubx. By contrast, ecdysone modifies AbdA function, whose activity is switched during remodelling towards a new genetic program that leads to differentiated cells with function, cell behaviour and transcriptional activity characteristic of the adult. Segment A6-A7 programmed cell death does not depends on abdA function. a.m., aorta myocytes; h.m., heart myocytes; t-c.m., terminal chamber myocyte.