ESR1 and hydrops fetalis: We found that the capillary density, measured as microvessels per cardiomyocyte, of HF mice treated with the ERβ-agonist DPN was similar to that of CTRL (sham-operated mice, 1 ± 0.1 in DPN vs. 0.62 ± 0.06 in HF and 1 ± 0.03 in CTRL, Fig. 5), while there was no difference in capillary density between the ERα-agonist PPT and the HF group (0.58 ± 0.04, Fig. 5b).