Lymphatic Vessel Function (LVF) by NIRF. For NIRF, a total of 9 SV40-lacZ mice ages 6–11 months were used. Mice were fed a low-chlorophyll diet for 2 weeks to reduce auto-fluorescence in the intestinal region and the abdominal hair was removed. Mice were anesthetized with isofluorane and received 200 μL Gd-Cy5.5 intravenously (dose of 500 mg/kg), and the accumulation of Cy5.5 into the urinary bladder was followed over time (A – F). Additional mice, represented in G-J, have their abdomen opened and the gastrointestinal tract removed to permit better visualization of the pelvic floor. NIRF of the regions within red circles on A-F is represented as average ± SEM of the integrated density × 107 (K). The numbers in each segment indicate the time lapse after i.v. administration of Gd-Cy5.5. Outside the urinary bladder, Cy5.5 accumulated in the kidneys (green arrows) and in lymph sacs (blue arrows in G, I, and J).