Distribution of anterogradely-labeled VGluT2-IR and CGRP-IR terminals across lamina I. Quantification of total and anterogradely-labeled VGluT2 and CGRP immunoreactivity in medial, mid and lateral regions of lamina I. 3D colocalisation analysis and volume quantification was performed on regions of interest spanning lamina I within the high resolution confocal z-stacks at each location as shown in Figure 4. Analysed regions extended from the boundary of Lissauer's Tract and lamina I to a depth of 60 μm within the dorsal horn, which spanned the region where anterogradely-labeled VGluT2-IR terminals were observed. The dimensions of each analysed region was 80 × 60 × 10 μm. Values are expressed as relative volumes normalized against the maximum volume of CGRP-IR terminals in any of the regions for each dorsal horn section. The relative proportion of Neurobiotin-labeled VGluT2-IR terminals compared with the total volume of VGluT2-IR terminals was significantly less in lateral regions of lamina I compared with medial and mid regions of lamina I (asterisk: p ≤ 0.05 for this comparison). The relative proportion of Neurobiotin-labeled CGRP-IR terminals compared with the total volume of CGRP-IR terminals was consistent across all three regions. Two-way ANOVA with Bonferroni post-hoc comparisons; n = 6 sections from 4 animals.