Characterization of collagen alignment and microscopic distribution in human amniotic membranes subjected to cyclic tensile strain. Collagen fibre alignment in specimens from the cervical amniotic membrane (CAM) or placental regions (PAM) was confirmed by second harmonic generation (SHG) imaging. Yellow arrow in (A) show direction of applied strain and collagen fibre alignment by SHG confocal microscopy (B) after application of cyclic tensile strain (2% CTS, 1 Hz) with the angle of orientation clearly distributed in one direction (C,D). Comparison of SHG intensity values in CAM and PAM specimens after application of CTS for 24 hr are shown in (E). Representative SHG confocal images are shown in (F) for n = 16 replicate fields of view from two donors (scale bar = 100 µm). Temporal changes in SHG intensity analysis after application of CTS for 0, 2 and 24 hours in CAM and PAM specimens are shown in (G). Error bars in (E,G) represent the mean and SEM values of n = 16 replicates from four donors.