Caulobacter crescentus stalked cell prepared by plunge-freezing in liquid ethane and imaged by cryo-TEM on FEI Tecnai F20. This bacterium is a powerful model for the study of cell-cycle regulation and differentiation as it exists both as an immobilized stalked cell and a motile swarmer cell. It is also particularly useful for prokaryotic structural studies using cryo-electron tomography due to its relatively small size. Image by Dr. Christos Savva, MIC .