An Electron Microscopic Investigation of the Cell Wall Organization of Conifer Tracheids and Conifer Cambium

Abstract

An electron micro-graph of a replica of the inner surface of the secondary cell wall of a conifer tracheid, demonstrating the almost transverse orientation of the microfibrils in this layer, is presented. This evidence provides confirmation of the type of cell wall organization of conifer tracheids proposed in other investigations on the basis of X-ray and optical evidence and of microscopic examination. The existence of fibrils of 50-100 A in diam. has been demon-strated in cell wall fragments obtained by the disintegration of cambium initials and of conifer tracheids. It is suggested that these microfibrils may correspond to the "micelles" or "crystalline regions" inferred from X-ray examination.