Collagen fibrils diameter

Bradshaw, A. D., Puolakkainen, P., Dasgupta, J., Davidson, J. M., Wight, T. N., and Sage, E. H. (2003). SPARC-null mice display abnormalities in the dermis characterized by decreased collagen fibril diameter and reduced tensile strength. J. Invest. Dermatol. 120, 949-955. 

Sanders, J. E., and Goldstein, B. S. (2001). Collagen fibril diameters increase and fibril densities decrease in skin subjected to repetitive compressive and shear stresses. J. Biomech. 34, 1581-1587. 

Moeller, H. D., Bosch, U., and Decker, B. 1995. Collagen fibril diameter distribution in patellar tendon autografts after posterior cruciate ligament reconstruction in sheep—changes over time. / Anat 187 161-67. 

Col Hal null mice have fibril diameter abnormalities in the early postnatal stage but the adult showed no significant differences. Type XIV collagen might function early in development regulating the entry of fibril intermediates into lateral fibril growth. ... 

Fig. 4. A model for the possible relationship between crystalline and disordered regions within a collagen fibril. The cross-sectional model of a 50-nm diameter fibril shows regions of crystallinity interfaced by grain boundaries. The individual crystalline unit cells are shown and the gap region is represented by a darker color. The axial projection of a single microfibrillar unit is also shown. Based on die structures developed by Hulmes et al. (1995) and adapted with permission from Hulmes et al (2002).

Type V collagen integration in corneal tissue from both avian and mammalian sources points to heterotypic collagen interactions providing some basis for fibril diameter regulation (White et al, 1997). Indeed, the triple-helical structure of Type V collagen alone has been shown to be an important factor in regulating the fibril diameter of Type V/Type I heterotypic fibrils in vitro (Adachi and Hayashi, 1986). 

Work by Haston et al. (2002) also indicates that acidic glycoprotein (AGP) influences Type II collagen fibrillogenesis, where in vitro studies show that low concentrations of AGP produced decreases in fibrillogenesis rate and fibril diameter. High concentrations produced fibrils at a rate and diameter dependent on fucosylation of AGP. Highly fucosylated AGP produced narrow fibrils, and poorly fucosylated AGP produced thicker fibrils. 

In mature tendon, collagen fibril bundles (fibers) have diameters between 1 and 300 mm and fibrils have diameters from 20 to over 280 nm (Figure 3.28). The presence of a crimp pattern in the collagen fibers has been established for rat tail tendon as well as for patellar tendon and anterior cruciate ligament the specific geometry of the pattern, however, differs from tissue to tissue. It is not clear that the crimp morphology of tendon is actually present in tendons that are under normal resting muscular forces. 

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