Anatomy of the fetal membranes: insights from spinning disk confocal microscopy

Abstract

Purpose The fetal membranes are essential for the maintenance of pregnancy, and their integrity until parturition is critical for both fetal and maternal health. Preterm premature rupture of the membranes (pPROM) is known to be an indicator of preterm birth, but the underlying architectural and mechanical changes that lead to fetal membrane failure are not yet fully understood. The aim of this study was to gain new insights into the anatomy of the fetal membrane and to establish a tissue processing and staining protocol suitable for future prospective cohort studies. Methods In this proof of principle study, we collected fetal membranes from women undergoing vaginal delivery or cesarean section. Small membrane sections were then fixed, stained for nucleic acids, actin, and collagen using fluorescent probes, and subsequently imaged in three dimensions using a spinning disk confocal microscope. Results Four fetal membranes of different types were successfully processed and imaged after establishing a suitable protocol. Cellular and nuclear outlines are clearly visible in all cases, especially in the uppermost membrane layer. Focal membrane (micro) fractures could be identified in several samples. Conclusion The presented method proves to be well suited to determine whether and how the occurrence of membrane (micro) fractures and cellular jamming correlate with the timing of membrane rupture and the mode of delivery. In future measurements, this method could be combined with mechanical probing techniques to compare optical and mechanical sample information.

mRNA and Protein Expression in Human Fetal Membrane Cells: Potential Biomarkers for Preterm Prelabor Rupture of the Fetal Membranes?

“…In normal term pregnancies, a similar, albeit not preterm senescence, is a physiologic requirement for natural progression of labor mechanisms [14,15]. Another characteristic of fetal membranes from pPROM deliveries is the increased number and size of the so-called "microfractures" in the amnion [16][17][18], which are characterized by (1) an altered morphology of the amnion epithelial cells, (2) a localized damage of the subepithelial basement membrane, (3) tunnels in the collagen rich extracellular matrix, and (4) the presence of migrating cells in the tunnels. Similar observations have been detected in the chorion, although it was more difficult to confirm because of its multilayer composition [16].…”