Chemical structure of the mass fraction of hydrogen (red lines), helium (green lines), carbon (blue lines), and oxygen (purple lines) as a function of interior mass for the considered 10 M_⊙ star. Panels E, F, G, and H correspond the evolutionary points labelled E, F, G, and H in Fig. 1, respectively. Left panels: for the 10 M_⊙ stars with Z = 0.014 but with different initial rotational velocities, v_ini = 0 km s⁻¹, 120 km s⁻¹, and 350 km s⁻¹. Right panels: for the 10 M_⊙ stars with Z = 0.0008 but with different initial rotational velocities.