SHH and hydrops fetalis: Notably, different signals lead to diverse characteristics during the life of HFSCs, Wnt/β-catenin can fuel HFSC activity for HF renewal, Shh signalling can improve quiescent-HFSCs proliferation, Notch signals can stop the differentiation programmes of HFSCs, BMP signals can modulate or reinforce the quiescence of HFSCs, the apoptotic pathway can respond to damage and induce self-cleaning.