Figure 4

Scanning electron micrographs of subgingival dental plaque. (a) Numerous ‘open tubule’ structures (solid arrow). An extensive web of extracellular strands can be seen (broken arrow) encompassing the tubules and also several chains of intact short rod-shaped microorganisms. Membrane-associated vesicles can be seen (wide ‘v’ arrow). (b) A single ‘open tubule’ (solid arrow) surrounded by intact cells (c). (a) ×20,000 magnification; (b) ×50,000 magnification.