Double immunofluorescence staining of Na +-K +-ATPase α1 (NKA)/LIM Homeobox 2 (LHX2) and Na +-K +-2Cl- cotransporter 1 (NKCC1)/LHX2 showed that HF-specific marker, LHX2, was detected only in the IFPs of C57BL/6 mice (Fig. 2e3, f2), whereas ESG-specific markers, NKA or NKCC1, were detected in the footpads and IFPs of C57BL/6 mice, and the footpads of SD rats (Fig. 2g–h). Here, TAC1 is linked to hydrops fetalis.