The application of stereo-micrography in the high voltage electron microscope to studies of cell-wall structure and deposition.

Abstract

SUMMARYStereo‐pairs taken from thick sections have proved useful in solving two problems concerned with the unusual cell walls of collenchyma. These are the three‐dimensional architecture of the cellulose microfibril skeleton of the wall and the organization of the plasmalemma and its derivatives, the paramural bodies.The basic structure of the wall is lamellate, as has been known for some decades, but the fine details of the lamellation have been the subject of controversy. A model has already been deduced on the basis of thin‐section work, but stereo‐micrography presents the opportunity of direct observational confirmation, as well as more detailed information.Wall deposition involves both the normal plasmalemma and the elaborate paramural bodies derived from it. The high voltage microscope presents the opportunity of looking at membranes in diagonal and face views, impossible in conventional ultrathin sections. In this way an increased knowledge of the structure of the membrane, as revealed in positively stained sections, has been obtained, as well as a more detailed picture of its configuration in the cell. The paramural bodies are elaborate tubular, lamellar or multivesicular bodies, continuous with the plasmalemma. Stereo‐micrography provides a much clearer view of their organization than has been possible heretofore.