3. 3D native villous tree organisation: altered
surface-volume relations in pre-eclampsia
Villous 3D shapes were highly varying (Figures 3A-D). Depending on
achievable imaging depth, linkages of terminal villi, intermediate
villi, and stem villi, could be visualised. The investigated EO-PE
placenta had large knob-like villous endings (Figure 3A) characteristic
of PE placenta. These knob-terminals were not uncommon and frequently
present on villous tips (Figure S7). Term control placenta had shorter
but highly condensed villi (Figure 3B), while branching appeared
excessive in an IUGR case (Figure 3C). Notable is that the LO-PE
placenta had highly varying regions with limited branching (Figure 3D)
and highly branched villi (Video S1). Segmentation procedures of
intermediate and terminal villi are illustrated in Figures S8-S11.
Quantitative results indicated that villous surface area increases
disproportionally to volume in investigated PE placentas (Figure 3E).
Diffusion surface area and villous volume had a positive linear relation
in term control placenta, whereas in PE a linear relation between
surface area and volume was absent (Figures 3E, 3F).
The SA/vol ratio provides a measure for easiness of diffusive transport
and branching is a biological mechanism to increase the SA/vol ratio. No
significant difference was found between the SA/vol ratio of chorionic
villi of control- and PE or IUGR placenta (Figure 3G). However, the
villous SA/vol ratio tended to be highest in LO-PE placenta, which
suggests increased villous branching compared to term placenta (Figure
3G). Notably, the villous SA/vol ratio was lowest in the term IUGR
placenta (Figure 3G), while villi appeared highly branched (Figure 3C).