title: Collagen Fiber Orientation in Primate Long Bones.
abstract: Studies of variation in orientation of collagen fibers within bone have lead to the proposition that these are preferentially aligned to accommodate different kinds of load, with tension best resisted by fibers aligned longitudinally relative to the load, and compression best resisted by transversely aligned fibers. However, previous studies have often neglected to consider the effect of developmental processes, including constraints on collagen fiber orientation (CFO), particularly in primary bone. Here we use circularly polarized light microscopy to examine patterns of CFO in cross-sections from the midshaft femur, humerus, tibia, radius, and ulna in a range of living primate taxa with varied body sizes, phylogenetic relationships and positional behaviors. We find that a preponderance of longitudinally oriented collagen is characteristic of both periosteal primary and intracortically remodeled bone. Where variation does occur among groups, it is not simply understood via interpretations of mechanical loads, although prioritized adaptations to tension and/or shear are considered. While there is some suggestion that CFO may correlate with body size, this relationship is neither consistent nor easily explicable through consideration of size-related changes in mechanical adaptation. The results of our study indicate that there is no clear relationship between CFO and phylogenetic status. One of the principle factors accounting for the range of variation that does exist is primary tissue type, where slower depositing bone is more likely to comprise a larger proportion of oblique to transverse collagen fibers. Anat Rec, 300:1189-1207, 2017. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York.
authors.forename: Johanna
authors.identifier: http://orcid.org/0000-0001-9847-165X
authors.initials: J
authors.lastname: Warshaw
authors.affiliation: Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York.|Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, New York.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Bromage
authors.affiliation: Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Terranova
authors.affiliation: Thomas Hill Emeritus Professor, Department of Orthodontics, Case Western Reserve University, Cleveland, Ohio.
authors.forename: Donald H
authors.initials: DH
authors.lastname: Enlow
mesh_terms: D000818:Animals; D016723:Bone Remodeling / Q000502:physiology*; D001842:Bone and Bones / Q000033:anatomy & histology* / Q000502:physiology*; D003094:Collagen / Q000737:chemistry*; D008859:Microscopy, Polarization; D011323:Primates; D013314:Stress, Mechanical
chemical_list: D003094:Collagen
keywords: bone growth; bone histology; bone tissue types; collagen fiber orientation; mechanical adaptation; primates