Interference Reflection Microscopy and Related Microscopies and Cell Adhesion

Abstract

Interference reflection microscopy (IRM) produces images of the contact zone between a live cell and a planar substrate. Thus it provides a means of detecting the nature and size of the adhesive contact that a cell may form on an appropriate surface. The image arises from interference between the reflection from the plasmalemmal interface and that from the interface with the substratum, see Fig. 1 below. In some situations these two interfaces are one, namely when there is no gap between the cell and substrate and the adhesive contact is a smooth molecular one. In others there is an extensive, perhaps even continuous gap of some 5 nm to 30 nm between the two interfaces. At the moment only this technique and the closely related techniques of Fluorescence Energy Transfer microscopy and of Total Internal Reflection Fluorescence Microscopy allow visualisation and measurement of the features of the contact zone in living material. IRM led to the discovery of the focal contact (Izzard and Lochner 1976). The technique has been carelessly renamed by some ‘reflection interference contrast microscopy’; since all useful types of microscopy develop contrast the use of the word contrast is redundant. There are reasons to suspect that preparation methods for electron microscopy lead to much possible artefact in the contact zone : these possible problems are discussed later in this chapter. IRM and TIRFM avoid such problems.