Introduction & Methods
XRH was utilised to investigate the structural diversity of placental villi in humans and equids (horses and related species), which despite their common evolutionary origins exhibit markedly different placental structures that may influence nutrient transfer efficiency. By combining XRH with electron microscopy (EM), the study aimed to elucidate these structural differences and their functional implications.
Placental tissue samples from humans and equids were fixed, stained, and embedded in resin. The samples were then imaged using a custom Nikon XTH 225 ST μCT scanner, which generated high-resolution volume images of the placental tissue. Following XRH imaging, the samples were further imaged using serial block face scanning EM (SBF-SEM) to obtain detailed cross-sectional views at the nanometer scale.
Correlative Imaging
The combination of XRH and EM allowed for comprehensive multiscale imaging of the placental tissue down to indivudual villi. μCT-based XRH provided a broad overview of the three-dimensional microanatomy, while EM offered detailed insights into the cellular and subcellular architecture. This approach revealed significant structural differences between human and equid placental villi in terms of
- Surface Area to Volume Ratio (SA) – Equid villi exhibited a higher SA compared to human villi – suggesting an adaptation to enhance nutrient transfer efficiency.
- Vasculature, with equid villi showing deeper trophoblastic vessel indentations compared to human villi as further quantified using EM
The role of XRH
The use of XRH was crucial in quantitatively evaluating the complex structures of placental villi without destroying the samples. The ability to combine XRH with EM provides a comprehensive view that bridges microanatomy and cellular scales, offering deeper insights into tissue architecture and its implications.
