G Model
ARTICLE IN PRESS
YSCDB-1781; No. of Pages 7
Seminars in Cell & Developmental Biology xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Seminars in Cell & Developmental Biology journal homepage: www.elsevier.com/locate/semcdb
Review
The ultrastructure of bone as revealed in electron microscopy of ion-milled sections Henry P. Schwarcz ∗ School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada
a r t i c l e
i n f o
Article history: Received 4 March 2015 Received in revised form 22 May 2015 Accepted 28 June 2015 Available online xxx Keywords: Bone Ultrastructure Apatite Collagen Fibrils Gap zone Mineral lamellae Transmission electron microscopy Ion milling
a b s t r a c t Mineral makes up more than half the volume of bone, but its spatial and structural relationship to collagen and other proteins is still a matter of debate. Due to the nanometer-size of bone crystals this matter can be resolved only with transmission electron microscope (TEM) images. Using sections cut with an ultramicrotome, previous investigators determined most mineral lies in the 40 nm wide gap zone in collagen fibrils. Using less invasive sectioning methods (ion milling and focused ion beam [FIB]) reveals that most mineral is extrafibrillar, occurring in the form of mineral lamellae, polycrystalline plates 300 nm or more long, packed around collagen fibrils in stacks of four or more lamellae
ARTICLE IN PRESS
YSCDB-1781; No. of Pages 7
Seminars in Cell & Developmental Biology xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Seminars in Cell & Developmental Biology journal homepage: www.elsevier.com/locate/semcdb
Review
The ultrastructure of bone as revealed in electron microscopy of ion-milled sections Henry P. Schwarcz ∗ School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada
a r t i c l e
i n f o
Article history: Received 4 March 2015 Received in revised form 22 May 2015 Accepted 28 June 2015 Available online xxx Keywords: Bone Ultrastructure Apatite Collagen Fibrils Gap zone Mineral lamellae Transmission electron microscopy Ion milling
a b s t r a c t Mineral makes up more than half the volume of bone, but its spatial and structural relationship to collagen and other proteins is still a matter of debate. Due to the nanometer-size of bone crystals this matter can be resolved only with transmission electron microscope (TEM) images. Using sections cut with an ultramicrotome, previous investigators determined most mineral lies in the 40 nm wide gap zone in collagen fibrils. Using less invasive sectioning methods (ion milling and focused ion beam [FIB]) reveals that most mineral is extrafibrillar, occurring in the form of mineral lamellae, polycrystalline plates 300 nm or more long, packed around collagen fibrils in stacks of four or more lamellae
