Finite-element analysis of geometrical factors in micro-indentation of pollen tubes.

Micro-indentation is a new experimental approach to assess physical cellular properties. Here we attempt to quantify the contribution of geometrical parameters to a cylindrical plant cell's resistance to lateral deformation. This information is important to correctly interpret data obtained from experiments using the device, such as the local cellular stiffness in pollen tubes. We built a simple finite-element model of the micro-indentation interacting partners - micro-indenter, cell (pollen tube), and underlying substratum, that allowed us to manipulate geometric variables, such as geometry of the cell, cell radius, thickness of the cell wall and radius of the indenting stylus. Performing indentation experiments on this theoretical model demonstrates that all four parameters influence stiffness measurement and can therefore not be neglected in the interpretation of micro-indentation data.