Fig. 5. (a) Series of widefield fluorescence images showing the effect of hypericin-induced PDT on a single glioma cell incubated with hypericin and PI. Different stages of cell damage are deductible, including rounding of the cell body (b)–(d), membrane bleb formation (d)–(f), explosive membrane rupture ((g), yellow arrow), and finally cell death (h). The membrane rupture is accompanied by the release of cytoplasm content into the extracellular environment. The overall recorded fluorescence intensity is continuously increasing, which results from more PI entering the damaged cellular body and binding to RNA/DNA.