Development of dendritic cell aggregates in cultured Lin⁻c-kit⁺ HPCs-derived from TNF-Rp55^+/+ mice bone marrow. Morphologic observation was performed under a phase contrast microscope on cultured Lin⁻c-kit⁺ HPCs. Lin⁻c-kit⁺ HPCs were isolated from TNF-Rp55^+/+ or TNF-Rp55^−/− mice bone marrow cells and incubated for 14 days (14 d) as described in the Materials and Methods. Similar experiments were repeated three times and representative results are shown here. Original magnification × 100.