Time-dependent changes of microscopic localization of intravenously administered colloidal carbon particles in mouse...

Time-dependent changes of microscopic localization of intravenously administered colloidal carbon particles were studied in mouse lymph nodes. Carbon particles were preferentially trapped by postcapillary venules (PCV) immediately after injection, and migrated easily outside of PCV either through intercellular space of the PCV endothelium or by phagocytic process during the 1 hr after injection. Particles were thereafter up-taken by pericytes and macrophages around PCV during the 24 hr, and consequently distributed throughout the cortex and medulla. Finally, they migrated to the medullary lymphatic sinuses, and phagocytosed by endothelial cells. Redistribution process of particles via the lymphatic sinuses from the regional lymph was observed during 30 minutes or 10 to 14 days after injection in different lymph nodes.