Vertical cross-sections. Vertical (x-z) cross-sections of the three dimensional dataset. The scale for the z-axis is x10 times that of the x-axis. Upper panel: Original fluorescence image. Lower panel: SOFI image. Nearest neighbor smoothing was performed for the SOFI image in order to filter high frequency noise originated from long blinking intermittency of the quantum dots along the z axis (the acquisition time of each slice is 60s). Blue and red lines indicate the same cross-sections for the original and SOFI images respectively. Right Panel: the corresponding cross-sections for the original (red) and the SOFI (blue) images. The SOFI intensity profile clearly shows increased resolution along z. Scalebar: 1 μm along z and 20 μm along x.