title: Dark-field transmission electron microscopy of cortical bone reveals details of extrafibrillar crystals.
abstract: In a previous study we showed that most of the mineral in bone is present in the form of "mineral structures", 5-6nm-thick, elongated plates which surround and are oriented parallel to collagen fibrils. Using dark-field transmission electron microscopy, we viewed mineral structures in ion-milled sections of cortical human bone cut parallel to the collagen fibrils. Within the mineral structures we observe single crystals of apatite averaging 5.8±2.7nm in width and 28±19nm in length, their long axes oriented parallel to the fibril axis. Some appear to be composite, co-aligned crystals as thin as 2nm. From their similarity to TEM images of crystals liberated from deproteinated bone we infer that we are viewing sections through platy crystals of apatite that are assembled together to form the mineral structures.
authors.affiliation: School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada. Electronic address: schwarcz@mcmaster.ca.
authors.forename: Henry P
authors.initials: HP
authors.lastname: Schwarcz
authors.affiliation: Department of Materials Science and Engineering, Canadian Centre for Electron Microscopy, McMaster University, Hamilton, ON L8S 4K1, Canada.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: McNally
authors.affiliation: Department of Materials Science and Engineering, Canadian Centre for Electron Microscopy, McMaster University, Hamilton, ON L8S 4K1, Canada.
authors.forename: Gianluigi A
authors.initials: GA
authors.lastname: Botton
mesh_terms: D001031:Apatites / Q000032:analysis*; D001842:Bone and Bones / Q000737:chemistry*; D003094:Collagen / Q000032:analysis*; D006801:Humans; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008875:Middle Aged; D008903:Minerals / Q000032:analysis*
chemical_list: D001031:Apatites; D008903:Minerals; D003094:Collagen
keywords: Apatite; Bone; Collagen; Dark-field illumination; Fibril; Gap zone; Mineral structure; Overlap zone; Transmission electron microscopy