2016 Volume 81 Issue 2 Pages 225-230
Cell wall thickness is a quantity that must be known in order to calculate the stress applied to a cell wall along its plane by turgor pressure. Measuring the width of a cell wall section with transmission electron microscopy (TEM) is one of the typical methods of measuring cell wall thickness. However, the possible occurrence of artifacts in this method has not been tested so far. In the present study, the cell walls of the giant cylindrical cells of the xanthophycean alga Vaucheria frigida (Roth) C. Agardh were examined by TEM from thin sections made perpendicular to the longitudinal cell axis, and their morphology and thickness were compared under different preparation methods in order to evaluate the reliability of each method of measuring cell wall thickness. Cell wall morphology was not significantly different between specimens dehydrated with acetone and embedded in hydrophobic Spurr’s resin and those dehydrated with ethanol and embedded in hydrophilic LR White. However, the cell walls of the former were significantly thinner (ca. 250 nm) than those of the latter (ca. 450 nm). In addition, cell wall thicknesses measured using an atomic force microscope (as the difference in the levels between the top of an isolated cell wall and the surface of the substratum) were about 130 nm or less, remarkably smaller than those measured by TEM from thin sections. These results indicate that cell wall thickness measurements from thin sections may be affected by artifacts, and other reliable methods are needed for measuring wall thickness correctly.
