3D multiscale characterization of the human placenta: Bridging anatomy and histology by X-ray phase-contrast tomography.

The human placenta exhibits a complex three-dimensional (3D) structure with a interpenetrating vascular tree and large internal interfacial area. In a unique and yet insufficiently explored way, this parenchymal structure enables its multiple functions as a respiratory, renal, and gastrointestinal multiorgan. The histopathological states are highly correlated with complications and health issues of mother, and fetus or newborn. Macroscopic and microscopic examination has so far been challenging to reconcile on the entire organ. Here we show that anatomical and histological scales can be bridged with the advent of hierarchical phase-contrast tomography and highly brilliant synchrotron radiation. To this end, we are exploiting the new capabilities offered by the BM18 beamline at ESRF, Grenoble for whole organ as well as the coherence beamline P10 at DESY, Hamburg for high-resolution, creating unique multiscale datasets. We also show that within certain limits, translation to μCT instrumentation for 3D placenta examination becomes possible based on advanced preparation and CT protocols, while segmentation of the datasets by machine learning now remains the biggest challenge.