Developmental divergence of tendon : a comparison of the fetal development of functionally distinct tendons

Abstract

Tendinopathies cause some of the most prevalent disabilities in Canada, giving rise to both widespread suffering and socioeconomic stress. Effective treatments remain elusive, and the incidence of tendinopathy is increasing. In recent years, the implantation of artificial tendon has emerged as a possible method for restoring tendon function. However, attempts at developing implants that mimic tendon properties have been hindered by insufficient knowledge of tendon development. To improve collective understanding, the present research investigated the fetal development of two functionally distinct tendons with characteristics that, in maturity, are fine tuned for the distinct mechanical roles each class of tendon experiences in life: the bovine energy storing superficial digital flexor tendon and positional common digital extensor tendon. Functional intermolecular cross–linking and morphology were evaluated via hydrothermal isometric tension testing, transmission electron microscopy, and polarized light microscopy. Structural idiosyncrasies identified between the two functionally distinct tendons during gestation, across all three methods of analysis, suggested the combined effect of differences in other early developmental cues — rather than mechanoregulation — to be the principal catalyst for the initial divergence of multiple tendon–specific characteristics. This finding points to prenatal tendon development as a rich area for future study of the control mechanisms responsible for the structure of collagenous tissues.