Evolution of the stellar radius and the internal structure for the same models as in Fig. 1. The horizontal axis corresponds to the stellar mass, which is a time coordinate in the case of accretion. In each case, the upper line indicates the stellar radius, the other continuous and long-dashed lines indicate the boundary between radiation and convection. The thin blue dotted lines are iso-mass of 1, 2, 3, ..., 21 M_⊙ for the model computed with the new version of the code.