title: Evidence that collagen fibrils in tendons are inhomogeneously structured in a tubelike manner.
abstract: The standard model for the structure of collagen in tendon is an ascending hierarchy of bundling. Collagen triple helices bundle into microfibrils, microfibrils bundle into subfibrils, and subfibrils bundle into fibrils, the basic structural unit of tendon. This model, developed primarily on the basis of x-ray diffraction results, is necessarily vague about the cross-sectional organization of fibrils and has led to the widespread assumption of laterally homogeneous closepacking. This assumption is inconsistent with data presented here. Using atomic force microscopy and micromanipulation, we observe how collagen fibrils from tendons behave mechanically as tubes. We conclude that the collagen fibril is an inhomogeneous structure composed of a relatively hard shell and a softer, less dense core.
authors.affiliation: Department of Physics, University of California, Santa Barbara, California 93106, USA. tguts@physics.ucsb.edu.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gutsmann
authors.forename: Georg E
authors.initials: GE
authors.lastname: Fantner
authors.forename: Manuela
authors.initials: M
authors.lastname: Venturoni
authors.forename: Axel
authors.initials: A
authors.lastname: Ekani-Nkodo
authors.forename: James B
authors.initials: JB
authors.lastname: Thompson
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Kindt
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Morse
authors.forename: Deborah Kuchnir
authors.initials: DK
authors.lastname: Fygenson
authors.forename: Paul K
authors.initials: PK
authors.lastname: Hansma
mesh_terms: D000818:Animals; D016880:Anisotropy; D003094:Collagen / Q000737:chemistry* / Q000648:ultrastructure*; D046911:Macromolecular Substances; D008846:Micromanipulation / Q000379:methods*; D018625:Microscopy, Atomic Force; D011487:Protein Conformation; D051381:Rats; D013710:Tendons / Q000737:chemistry* / Q000648:ultrastructure*; D016474:Weight-Bearing
chemical_list: D046911:Macromolecular Substances; D003094:Collagen