ROR2 and hydrops fetalis: As shown in Fig. 2g, YFP+ Ror2 Ctrl HFSCs were fully maintained in the stem cell niche after HF regeneration was completed, but only ~82% of YFP+ HFSCs were recovered from the previous Ror2 cKO HFSC pool, suggesting that some Ror2 cKO HFSCs were lost during HF regeneration.