Villous tree morphology: exchange surface and volume
Villous branching establishes an increased diffusional surface and the villous SA/Vol reflects easiness of nutrient exchange. Similar to our findings (Figure 3E), a disproportional relation between surface area and volume has been reported in PE placentas based on a stereological approach51. However, some stereological estimates only observed altered exchange surface areas in IUGR cases, and not for PE alone52, 53. Stereology only provides estimates of 3D quantitative parameters while quantification of MPM images represents the intact 3D villi. 3D characterization by MPM will therefore aid in more accurate quantification of villous trees to confirm or reject abovementioned findings.