Fig. 2

Confocal microscopic images showing specific uptake of the fluorescent l-glucose derivative 2-NBDLG into mouse insulinoma MIN6 cells, which formed three-dimensional spheroids consisting of cells with nuclear heterogeneity. a Differential interference contrast image of MIN6 cells forming thick spheroids merged with 2-NBDLG fluorescence. Cells in the upper spheroid (a) exhibited strong 2-NBDLG fluorescence. b A single optical section of a nuclear image visualized by 4′,6-diamidino-2-phenylindole (DAPI) in a livecell condition. Cells in the upper spheroid (a) exhibited strong nuclear heterogeneity in morphology, whereas cells with evenly arranged small nuclei were seen in the lower one (b). c Merged image of (b) and 2-NBDLG fluorescence (a). Note that small cells bearing small nuclei (asterisk) also took up 2-NBDLG in the upper spheroid. Images were reproduced with permission from Sasaki A et al. [11]