Of all the parts of the human body, the stubby little discs between the bones in the spine represent one of the more remarkable feats of natures design.
Consisting of tough, rubbery rings of collagen with jelly-like centers, they compress with every step we take. They twist. They flex. Over a lifetime of wear and tear, they replenish their supportive matrix of collagen despite having no internal blood supply.
It is really a marvel of engineering, said Robert L. Mauck, who as a biomedical engineer at the University of Pennsylvania, has the chops to say that.