NID1 and hydrops fetalis: The remaining denuded HF epithelium was then embedded into an ECM environment that partially mimics aspects of the native HF mesenchyme and BM (i.e. Matrigel®, which is rich in the ß1 integrin ligands laminin, collagen IV, heparin sulfate proteoglycans, entactin, and growth factors [12,35,64], combined for greater stability with collagen I which represents the main dermal collagen).