Tendon collagen fibrillogenesis is a multistep assembly process as revealed by quick-freezing and freeze-substitution.
The ultrastructure of chick embryo tendons has been examined after quick-freezing by liquid helium and freeze-substitution. Several stages of collagen assemblies were observed: intracellular packing of SLS-like aggregates surrounded by membrane containing areas with a clathrin coat; fine non cross-striated filaments connecting the cell membrane at 1 pole of the cells and collagen fibrils; tufts of filaments directly linked to collagen fibrils. This study reveals that some stages are more constant and abundant than supposed (the intracellular SLS-like aggregates) and that other extracellular assemblies that were hypothesized but usually badly preserved by conventional electron microscopy are clearly captured by the method.
Mallein-Gérin
F
F
Laboratorie de Cytologie Moléculaire IBCP, CNRS UPR 412, Université Claude Bernard, Villeurbane, France.
Garrone
R
R
D000818:Animals; D002642:Chick Embryo; D003094:Collagen / Q000378:metabolism / Q000648:ultrastructure*; D015925:Cryopreservation; D005347:Fibroblasts / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods; D013710:Tendons / Q000648:ultrastructure*
D003094:Collagen