Coil-like structure of the inner core of chordae tendineae

Scanning electron microscopy was used to examine the chordae tendineae in young (approximately 20 years old) and old (approximately 85 years old) cadavers. A network of collagen fibrils was observed in both the outer and intersurface layers of the chordae tendineae. In young subjects, a regularly arranged series of disconnected collagenous ring-like structures surrounded the longitudinal collagen bundles forming the inner core of the chordae tendineae. In old subjects, the ring-like structures of the chordae tendineae were few or absent. The ring-like structures may be related to reducing mechanical stress during the tightening, twisting, and slackening of the chordae tendineae.