PDGFRA and hydrops fetalis: To evaluate changes in postnatal dermis that correlate with loss of HF forming ability, we labelled the dermis of PDGFRaH2BeGFP mice (with a histone H2B-eGFP reporter knocked into the Pdgfra locus) for markers that distinguish different fibroblast subpopulations at P2 (Driskell et al., 2013) (Fig. 3A,B).