Spinal microglia are critical mediators in the development of opioid tolerance. In this image, a variety of individual Iba1-labelled microglia from rat spinal dorsal horn sections are re-colored and compiled to form a cross-section of the lumbar spinal cord. Each microglia cell is unique and they show a variety of morphologies representative of the dynamic and reactive nature of microglia. For more information, see the article by Leduc-Pessah et al. (pages 10154–10172).