Figure 8.

Throughout gestation, there were no major changes to collagen (stained yellow-orange) fiber orientation in the anterior leaflet or chordae tendineae. Circumferential sections of the leaflet showed primarily circumferentially-aligned collagen fibers and the longitudinal sections of the strut chordae showed primarily longitudinally-aligned collagen fibers. Magnified sections of representative images of Movat-Pentachrome–stained mitral anterior leaflets (A,C,E) and strut chordae tendineae (B,D,F). (A,B) Early second trimester (111 days gestation). (C,D) Third trimester (219 days gestation). (E,F) Full term (270 days). Collagen is stained yellow-orange, glycosaminoglycans blue-green, and cell nuclei dark red-purple. Scale bar varies per image.