Movat-stained circumferential sections of the MVAC and MVF of 6-week-old, 6-month-old, and 6-year-old porcine valves. Both high magnification (column 1) and low magnification (columns 2 – 4) are shown. All images within a magnification type (high vs. low) are the same magnification to allow comparison of leaflet and layer thickness across age and leaflet region. Movat pentachrome staining preferentially stains different ECM elements certain colors (yellow = aligned collagen, black = elastic fibers, and green/blue = PGs / GAGs). Comparing regions, the MVAC fibrosa comprised a larger proportion of the valve than in the MVF. Across ages (regardless of region), an increase with collagen with increasing age was noted, especially in the fibrosa and ventricularis. Scale bar = 200 mm. Modified from Stephens EH, Jonge N de, McNeill MP, Durst C a, Grande-Allen KJ. Age-related changes in material behavior of porcine mitral and aortic valves and correlation to matrix composition. Tissue Eng A. 2010;16(3):867–78 with permission from Elsevier.