1. Structural Characterization of the Chordae Tendineae in Native Porcine Mitral Valves 
Jennifer Ritchie, MS, James N. Warnock, PhD, Ajit P. Yoganathan, PhD 
The Annals of Thoracic Surgery 
Volume 80, Issue 1, Pages (July 2005)
DOI: /j.athoracsur
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

2. Fig 1
Porcine mitral valve cut along the posterior leaflet showing the chordae insertion pattern. All six chordae shown here were used for the histologic and biochemical studies.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

3. Fig 2
Hematoxylin and eosin staining did not reveal any differences in the gross morphology between the various chords. Cell nuclei were stained dark blue, collagen fibers were stained dark pink, and elastin fibers were stained light pink. Sections are 5 microns in the radial directions. (Left) Anterior marginal chordae, 10×. (Right) Basal chordae, 10×. The middle layer of loose collagen can be seen separating from the inner collagen core.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

4. Fig 3
(A) Hematoxylin and eosin staining observed under fluorescent microscopy to observe directional crimping and (B, C) elastin fibers. The crimping is observed in the direction of loading. The middle layer of loose collagen does not contain the tight crimping as seen in the inner collagen core. Elastin fibers can be seen in the (A) longitudinal and (B) radial directions. Sections are 5 microns in each direction.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

5. Fig 4
Anterior strut chordae stained with Verhoeff counterstained with light green. The cell nuclei and elastin fibers were stained black and the surrounding tissue were stained green. Sections are 5 microns thick in both the radial and longitudinal directions. (Left) Strut, longitudinal, 40×. (Right) Strut, radial, 40×.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

6. Fig 5
Verhoeff and van Gieson stain of the chordae shows vessels in the middle layer of loose collagen and (right) in two vessels that were located in close proximity. The vessel with the thicker endothelial wall is considered an artery, and the other vessel is considered a vein. The collagen was stained red, the elastin and cell bodies were stained black, and the remaining tissue was stained yellow. Sections are 5 microns thick in the radial direction. (Left) Anterior marginal, radial, 10×, and (right) anterior strut, radial, 20×.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

7. Fig 6
Evidence of vascularization of the chordae tendineae of the mitral valve. (A) Number of vessels located in each chordae. Data represent mean values ± standard error of the mean (n = 11). *Shows significant difference (p < 0.05). (B, C) Immunohistochemistry performed with von Willebrand factor on the chordae. Sections are 5 microns in the radial direction. The endothelial cells were stained brown; other cell nuclei were stained blue; and surrounding tissue was stained light gray. (B) Endothelial surrounding the chordae. Strut chordae at 40×. (B) Endothelium lining the vessel wall. Strut chordae at 20×.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

8. Fig 7
Biochemical assay results. Data represent mean values ± standard error of the mean. *Shows significant difference (p < 0.05). (A) DNA content in the mitral valve chordae per mg of dry tissue. DNA was measured using a Hoechst fluorescent assay (n = 21). (B) Elastin content in the mitral valve chordae per mg of dry tissue. Elastin was measured using the Fastin Elastin assay kit (Biocolor, Ireland) (n = 7). (C) Amount of collagen per mg of tissue. Collagen content in the mitral valve chordae per mg of dry tissue. Collagen was measured using the Sircol collagen assay kit (Biocolor, Ireland) (n = 16).
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions

9. Fig 8
Three-dimensional model of the mitral valve chordae tendineae describing the histologic composition. The outer layer is composed of endothelial cells, the second layer is composed of loose collagen with elastin fibers interwoven, and the inner layer is composed of tightly bound collagen. Vessels were found in the second layer of loose collagen running from the papillary muscle to the mitral apparatus.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2005 The Society of Thoracic Surgeons Terms and Conditions