Twisted plywood architecture of collagen fibrils in human compact bone osteons

Ultrathin sections of decalcified human compact bone, observed by transmission electron microscopy, reveal that collagen fibrils can be distributed in the form of a superimposed series of nested arcs. This characteristic pattern has never been interpreted in previous works on compact bone structure. We demonstrate, by goniometric observations at the ultrastructural level, that such series of nested arcs are a consequence of the “twisted plywood”...