title: Different crimp patterns in collagen fibrils relate to the subfibrillar arrangement.
abstract: Collagen fibril ultrastructure and course were examined in different connective tissues by PLM, SEM, TEM, and AFM. In tendons, collagen fibrils were large and heterogeneous with a straight subfibrillar arrangement. They ran densely packed, parallel, and straight changing their direction only in periodic crimps where fibrils showed a local deformation (fibrillar crimps). Other tissues such as aponeurosis, fascia communis, skin, aortic wall, and tendon and nerve sheaths showed thinner uniform fibrils with a helical subfibrillar arrangement. These fibrils appeared in parallel or helical arrangement following a wavy, undulating course. Ligaments showed large fibrils as in tendon, with fibrillar crimps but less packed. Thinner uniform-sized fibrils also were observed. Fibrillar crimps seem to be related to the subfibrillar arrangement being present only in large fibrils with a straight subfibrillar arrangement. These stiffer fibrils respond mainly to unidirectional tensional forces, whereas the flexible thinner fibrils with helical subfibrils can accommodate extreme curvatures without harm, thus responding to multidirectional loadings.
authors.affiliation: Department of Human Anatomical Sciences and Physiopathology of Locomotor Apparatus, University of Bologna, Italy. marco.franchi3@unibo.it
authors.forename: Marco
authors.initials: M
authors.lastname: Franchi
authors.forename: Mario
authors.initials: M
authors.lastname: Raspanti
authors.forename: Carlo
authors.initials: C
authors.lastname: Dell'Orbo
authors.forename: Marilisa
authors.initials: M
authors.lastname: Quaranta
authors.forename: Viviana
authors.initials: V
authors.lastname: De Pasquale
authors.forename: Vittoria
authors.initials: V
authors.lastname: Ottani
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ruggeri
mesh_terms: D000818:Animals; D001011:Aorta / Q000648:ultrastructure; D003238:Connective Tissue / Q000648:ultrastructure*; D005205:Fascia / Q000648:ultrastructure; D005260:Female; D024022:Fibrillar Collagens / Q000648:ultrastructure*; D008023:Ligaments, Articular / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D010525:Peripheral Nerves / Q000648:ultrastructure; D051381:Rats; D012867:Skin / Q000648:ultrastructure; D013710:Tendons / Q000648:ultrastructure*
chemical_list: D024022:Fibrillar Collagens