Figure 3.

Microscopic examination of chordae tendineae from HH stage 44 chicken embryos (Gallus gallus). Various forms of microscopy were used to analyze the structure and composition of murine chordae. The top panel images (A–C) were obtained using laser scanning confocal microscopy. The collagen distribution in the chordae was determined. (A) Represents the chordae stained with an antibody to type I collagen (green). The extensive wavy pattern of the fibrils is observed. (B) The same section stained with an antibody to type VI collagen (red). The type VI collagen is observed dispersed near the type I collagen. (C) A higher magnification image of the chordae showing the nuclei of the cells (blue) and the extreme wavy collagen type I fibers (green). The middle panel contains images of a similar chordae obtained using scanning electron microscopy (SEM). (D) The image shows the surface of the chordae with the underlying collagen fibrils in an organized wavy orientation. (E) The chordae were cut in a cross-sectional manner to visualize the alignment of the collage fibers running the length of the chordae. (F) Higher magnification showing the cut ends of the collagen fibers and the tightly organized arrangement of the fibers. The lower panel contains images obtained using atomic force microscopy. (G) The surface of the chordae was visualized in tapping mode to show the general contour of the surface. (H) A higher magnification of the same area showing the individual collagen fibers and the “D-period” periodicity of a single fiber. (I) A 3D rendering of the surface topology of the cord using the data generated from the previous image. The scale bars in A–B equal 100 μm, C equal 20 μm. All other images contain scale information.