Fig. 7

Comparison of tracer fluorescence (integrated density) in axial sections at the 20 and 60 min time points per spinal level to assess the effect of time on tracer distribution. Each spinal cord level (“Level”) is expressed as the number of levels rostral (positive integers) or caudal (negative integers) to injection site. All error bars are expressed as SEM. a After grey matter injections, no statistical significant difference between the time points was observed in the fluorescence intensity in the grey matter. b Following injection of tracer in the white matter, no statistically significant difference was observed between the 20 and 60 min groups in the grey matter. However, on post hoc analysis there was significantly greater fluorescence at + 1 level rostral to the injection site after 60 min (****p < 0.0001). Similarly, after both c grey matter injections and d white matter injections, there was no overall statistical significant difference between the 20 and 60 min groups in the white matter. However, post hoc analysis demonstrated greater integrated densities at 60 min (compared to 20 min) − 1 level caudal (**p = 0.009) and + 1 level rostral (****p < 0.0001) to the injection site in c grey matter and d white matter injections respectively