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

Abstract

An electron micrograph of a replica of the inner surface of the secondarycell wall of a conifer tracheid, demonstrating the almost transverse orientationof the microfibrils in this layer, is presented. This evidence provides confirmationof the type of cell wall organization of conifer tracheids proposed inother investigations on the basis of X-ray and optical evidence and of microscopicexamination. The existence of fibrils of 50-100 A in diameter has beendemonstrated in cell wall fragments obtained by the disintegration of cambiuminitials and of conifer tracheids. It is suggested that these microfibrilsmay correspond to the "micelles" or "crystalline regions" inferred from X-rayexamination.