title: Deformation mechanisms of human amnion: Quantitative studies based on second harmonic generation microscopy.
abstract: Multiphoton microscopy has proven to be a versatile tool to analyze the three-dimensional microstructure of the fetal membrane and the mechanisms of deformation on the length scale of cells and the collagen network. In the present contribution, dedicated microscopic tools for in situ mechanical characterization of tissue under applied mechanical loads and the related methods for data interpretation are presented with emphasis on new stepwise monotonic uniaxial experiments. The resulting microscopic parameters are consistent with previous ones quantified for cyclic and relaxation tests, underlining the reliability of these techniques. The thickness reduction and the substantial alignment of collagen fiber bundles in the compact and fibroblast layer starting at very small loads are highlighted, which challenges the definition of a reference configuration in terms of a force threshold. The findings presented in this paper intend to inform the development of models towards a better understanding of fetal membrane deformation and failure, and thus of related problems in obstetrics and other clinical conditions.
authors: Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland. Electronic address: mauri@imes.mavt.ethz.ch.
authors: Arabella
authors: A
authors: Mauri
authors: Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland.
authors: Alexander E
authors: AE
authors: Ehret
authors: Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland.
authors: Michela
authors: M
authors: Perrini
authors: Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland.
authors: Caroline
authors: C
authors: Maake
authors: Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland.
authors: Nicole
authors: N
authors: Ochsenbein-Kölble
authors: Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland.
authors: Martin
authors: M
authors: Ehrbar
authors: Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK.
authors: Michelle L
authors: ML
authors: Oyen
authors: Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Swiss Federal Laboratories for Materials Science and Technology, EMPA, 8600 Dübendorf, Switzerland.
authors: Edoardo
authors: E
authors: Mazza
mesh_terms: D000650:Amnion / Q000502:physiology / Q000648:ultrastructure*; D001696:Biomechanical Phenomena; D003094:Collagen / Q000648:ultrastructure; D019277:Entropy; D005260:Female; D006801:Humans; D036641:Microscopy, Fluorescence, Multiphoton; D011247:Pregnancy
chemical_list: D003094:Collagen
keywords: Human amnion; In situ experiments; Mechanical behavior; SHG microscopy