Figure 8. Representative confocal images of lymph nodes sections 6 h after periocular administration of 20 nm nanoparticles. Lymphatic circulation plays a role in the clearance of nanoparticles (20 nm) after periocular administration. Representative confocal images of lymph nodes sections, 6 h post periocular administration of 20 nm nanoparticles. Nanoparticles (20 nm; green) were administered to SD rats, live (Panels B, E, and H) and dead (Panels C, F, and I) by periocular injection. Lymph nodes, namely, cervical (Panels A-C), axillary (Panels D-F), and mesenteric (Panels G-I), were analyzed for the presence of nanoparticles by confocal microscopy. Lymph nodes of undosed SD rats were treated as controls (Panels A, D, and G). Green fluorescence associated with nanoparticles was observed in lymph node sections of live, but not dead, SD rats 6 h post periocular administration of nanoparticles. This suggests that in live animals lymphatic drainage delivered nanoparticles to various lymph nodes, however in dead rats, which are devoid viable lymphatic system, nanoparticles could not be detected in lymph nodes.