Rumen bacteria. Coloured Transmission Electron Micrograph (TEM) of unidentified bacteria in the rumen of a cow. A number of anaerobic bacteria are visible (red), sectioned through to show the cell wall and cell contents. At lower frame (grey) is cellulose plant material which is in the process of being digested by these bacteria. Cows, like all herbivorous ruminants, have a complex stomach divided into chambers. One such chamber is the rumen which contains rumen bacteria. Here, the bacteria live symbiotically in large numbers and serve to break down cellulose in plants, making plant matter digestible to cows, sheep, goats and deer. Magnification: x35,300 at 6x4.5cm size.