THE ELEMENTARY CELLULOSE FIBRIL IN PICEA-ABIES - COMPARISON OF TRANSMISSION ELECTRON-MICROSCOPY, SMALL-ANGLE X-RAY-SCATTERING, AND WIDE-ANGLE X-RAY-SCATTERING RESULTS

The wood cell wall is built with elementary cellulose fibrils (ECF) ha ving a uniform thickness of 25 +/- 2 Angstrom. This was shown by inves tigating the same samples independently with three different experimen tal techniques, transmission electron microscopy (TEM), wide-angle X-r ay scattering (WAXS), and small-angle X-ray scattering(SAXS). Discrepa ncies between results from these techniques discussed in many earlier studies did not appear in the present work. In particular, it was show n that the size distribution measured on TEM pictures is exactly the s ame as the one estimated from SAXS, if the statistical error introduce d by the grain size of the contrasting medium is taken into account fo r the evaluation of the pictures. The fact that native cellulose fibri ls have a uniform thickness in the wood cell wall-which is not the cas e in many other cellulose preparations-could indicate a biological reg ulation of the thickness, possibly to achieve better mechanical stabil ity of the cell wall.