Untreated MCF-7 cells (a and b); asterisk-cytoskeleton, arrow-nuclei, circle-typical cell cluster. MCF-7 cells treated with IC50 value of silymarin (c and d); arrow-condensed chromatin, asterisk-condensed cell, circle-lacerated cell cluster, small circle-fragmented nuclei and MCF-7 cells treated with IC50 value of silymarin-loaded SLN (e and f) for 24 h; circle-shrunken cell cluster with decreased number of cells, arrow- excessive chromatin condensation, asterisk-highly perforated cytoskeleton.