Banded patterns in liquid crystalline phases of type I collagen: relationship with crimp morphology in connective...

Solutions of type I acid soluble collagen were studied in light and electron microscopy at concentrations over 40 mg/ml. Banded patterns spontaneously emerge in samples observed between crossed polars between slide and coverslip. The textures are interpreted as precholesteric, appearing at the transition between the isotropic phases, due to random molecular order, and the cholesteric phase corresponding to a highly organized three-dimensional structure. Type I collagen banded patterns correspond to regular undulations of the molecular directions with an observed periodicity in the range of 1 to 10 microm. This interpretation is verified by ultrastructural analysis of precholesteric samples gelled under ammonium vapors. Results are discussed in regard to banded patterns described either within synthetic polymer systems or within collagen extracellular matrices. Self-assembled liquid crystalline phases of collagen generate crimp morphologies. Their possible relationship with early secretion steps in the development of connective tissues is discussed.