Absolute Fluorescence measurements.

Observed mean fluorescence (in millions of photons per second per centimeter square per steradian (p s−1 cm−2 sr−1)) measured by ROI over the spine (A). Weeks indicate the time in weeks from the start of the experiment, time in minutes indicates the fluorescence measured at that time point (post-TTc injection) on the week of the experiment. P-values are for simple T-tests comparing values at 60 minutes between week 0 and every following week. Both raw values (absolute fluorescence at 60 minutes) and corrected values (fluorescence at 60 min minus fluorescence at 0 min) are compared.