Fig. 2. Podosome rosettes are adherent structures. (A) Observation of 3T3 fibroblasts by total internal fluorescence microscopy show that podosomes are dense actin dots. (B) Confocal interference reflection microscopy (CIRM) revealed that podosomes are structures in close contact with the substrate and are therefore involved in cell adhesion. (C) Rosette in 3T3 fibroblast viewed by fluorescence. This ring-shaped structure is composed of a large number of podosomes, all adherent to the substrate (D), as observed with CIRM. Furthermore, they can coexist with other adherent structures such as focal contacts. Bars, 10 µm.