Mechanisms for the following parity-breaking effects are examined: a) asymmetry in the emission direction of the light fission fragment; b) rotation of the neutron spin around the direction of its momentum in a medium and the difference between the cross sections for the capture of right-hand- and left-hand-polarized neutrons; c) circular polarization and asymmetry in the angular distribution of $\gamma$ rays. There is particular emphasis on the reasons for the enhancement of these effects in heavy nuclei. Theoretical results are compared with experimental data.