This scanning electron micrograph shows mycoplasma (colorized pink), a genus of bacteria that lack a cell wall. Without a cell wall they are unaffected by many common antibiotics, such as penicillin, or other beta-lactam antibiotics that work by targeting cell wall synthesis. These mycoplasma are shown on the surface of osteoblast cells, cells that are involved in the creation of new bone.
Scanning electron micrograph 2007. Wellcome Images. Kevin MacKenzie