A Vacuolar System in Cells of Agrobacterium tumefaciens as shown by Electron Microscopy of Ultra-thin Sections

Abstract

ELECTRON microscope studies of ultra-thin sections of the cells of several species of bacteria made by different workers have shown a regular structural pattern which can be summarized as follows : a definite cell wall, a cytoplasmic membrane (Chapman¹), a granular cytoplasm with one or more round, dense inclusions called chondrioids (Kellenberger et al.²), and a more or less central core which is irregular in shape and low in density to the electron beam. Comparative studies of stained preparations with the light microscope have led various workers to associate this core with nuclear structures, and it has been called vesicular nucleus, kernvacuole, kernäquivalent, nucleoide, nuclear sites, and nuclear apparatus. Reticulated structures within this core have been considered to be nuclear material, deoxyribonucleic acid or even chromosomes.