Activation of microglia in L4 spinal cord segment following nerve injury. (A) Epifluorescence imgage of L4 spinal cord segment following nerve injury. Left half side in the image represents the nerve injured side. Laminae of dorsal and ventral horns are indicated by the numbers. Note the difference of microglia between two sides. (a-f) Confocal laser scanning microscopy observation of microglia from the same laminae as shown by panel A. (a-c) Microglial cells from lamina II, IV and IX of nerve injured side, respectively. (d-f) Microglial cells from lamina II, IV and IX of the intact side, respectively. Bar = 400 μm in A, 20 μm in a – f.