Biodistribution of Al particles. a) Morin stain for aluminum shows rounded alum cytoplasmic agglomerates within muscle macrophages after i.m. vaccine administration in C57 mouse; b) Morin stain confirms that phagocytosed Al-Rho nanohybrids are associated with Al and form particles similar in size to alum agglomerates; c-e) Al-Rho nanohybrids show a time-dependent distribution in DLNs, spleen, and brain strikingly similar to that of FLBs; f) Al-Rho injected by the s.c. route translocate to DLNs and spleen, as observed with the i.m. route; g,h) Ly6C immunophenotyping of CD11b+ cells that have ingested Al-Rho: most are Gr1+/Ly6C+ both in DLNs at d4 (g) and spleen at d21 (h). (histograms: n = 3 per group, mean ± SD, * P <0.05, ** P <0.01, *** P <0.005; bar in a: 10 μm). d, day; DLN, draining lymph nodes; FLBs, fluorescent latex beads; n, number.