Ultrastructural changes in HeLa cells after 24 h of treatment with emodin, vinblastine and the combined action of both compounds. (A) Control—a cell with the correct nucleus and organelles with normal structure. Cells after the action of emodin (E 40 µM) with an increased number of Golgi apparatuses with swollen cisterns. Cells treated with emodin (E 80 µM)—extensive Golgi apparatuses with dispersed cisterns, numerous autophagic vacuoles, primary lysosomes and swollen mitochondria. Cells treated with vinblastine (VBL 10 µM)—the presence of swollen mitochondria with damaged cristae, autophagic vacuoles, lysosomes and cytoskeleton elements. Cells after the combined action of the compounds (E 40 µM and 80 µM + VBL 10 µM)—highly swollen and completely electron-transparent mitochondria with cristae drawn into the membrane, numerous lysosomes and autophagic vacuoles. Explanation of abbreviations: N—cell nucleus, M—mitochondria, VA—autophagic vacuoles, AG—Golgi apparatus, L—primary lysosomes, MT—microtubules, ER—rough endoplasmic reticulum. Magnification × 11,500. (B) Change in mitochondrial size as a function of the concentration of the test compounds. Data correspond to mean values ± standard error (S.E.) and are representative of three parallel experiments. The differences were statistically confirmed at: ** p < 0.01, *** p < 0.001.