Ultrastructural morphology of A549 cells: control (a, b), treated with free Selol (S) (c, d) and treated with Selol-PVM/MA nanocapsules (SPN) (e, f). Note the integrity of the mitochondria (M), endoplasmic reticulum (ER), plasma membrane (PM), nucleus (N), nuclear envelope (NE), and cytosol of the control cells. An endocytosed Selol droplet is shown with an arrow in c. Endosomes, as indicated by an arrow in d, were usually identified with the free Selol treatment. Cytoplasm characteristic of necrotic cells can be observed in e (arrow). Intense formation of vacuoles (V) containing cellular organelles and changes in the morphology of mitochondria (arrowhead) can be evidenced in d and f.