Quantification of particles inside individual cells. Intracellular particle numbers were analysed in cultures exposed to 1 μm, and 0.078 μm polystyrene particles with the software Diacount. Epithelial cells (Ep). Number of intracellular particles was counted in individual cells. Data are expressed as the mean of 3–4 experiments (10–14 cells scanned per experiment by LSM).