Figure 3

Fluorescence micrographs of liver section. Following intravenous administration of fluorescently labeled substances, sections were prepared as described in the Methods section. A heterogeneous distribution of yellow fluorescence from TRITC-labeled monodisperse polymer particles (MDPP) phagocytosed by Kupffer cells was located mainly in the periportal region of the liver acinus (arrows) (A). Green fluorescence along the lining of the liver sinusoids identifies endocytosed FITC-formaldehyde-treated serum albumin (FSA) by liver sinusoidal endothelial cells (LSEC), while the localization of phagocytosed MDPP is shown by arrows (B). Uptake of FITC-FSA (arrowheads) and MDPP (arrow) is shown more clearly at higher magnification in C. (Scale bars; A: 80 μm, B: 20 μm, C: 8 μm).