Morphology of keratinocytes exposed to tanshinone IIA. Detection of tanshinone IIA-induced apoptosis in keratinocytes under light microscopy. With increasing concentrations of tanshinone IIA, different features of chromatin clumps (several different forms of chromatin aggregation, arrows) were clearly observed. Detection of apoptotic cells gradually increased in a dose-dependent manner. Marked morphological changes of cellular apoptosis, including condensation of chromatin and nuclear fragmentation, were clearly observed. Each experiment was performed in triplicate. The scale bar in the first panel represents 50 μm for all sections.