The number of astrocyte (GFAP-positive) or microglia (OX42-positive) cell bodies in the dorsal horn of spinal cord sections collected from rats receiving intrathecal morphine (15 μg, MS), or vehicle (saline). No significant difference was observed between treatment groups. Data represent means ± s.e.m. for n = 6-8 sections (150 μm × 150 μm) per rat from n = 4-6 per group. Statistical analyses were performed using an unpaired t-test.