[en] Evidence obtained by a number of workers of the phase transition, characterized by a reordering of nuclear structure such that the ground state has a strong pion-field component accompanied by a long-range ordering of nucleon spins implied by the spin dependence of the pion-nucleon interaction, of nuclei into a pion condensate, is reviewed. In particular, results obtained using electron and proton scattering to explore the high momentum transfer properties of the Jsup(π) = 1, T = 1 state in ¹²C are discussed. It is shown that there is no evidence for a sizeable amplification of the pion field in nuclei and the repulsive short-range correlations accompanying one-pion exchange seem to be sufficiently strong to prevent the nucleus from approaching critical conditions. There are many hints that repulsive forces are in fact strong in spin-isospin excitation channels, from the positions of unnatural parity states, from the strength functions of Gamow-Teller resonances and from the mass-dependent quenching of magnetic transitions at low momentum transfers. (U.K.)