Corrections to the spectra describing Jeans instability and acoustic vibrations due to the consideration of annihilation processes in the hydrodynamic model of the gravitationally neutral Universe are obtained. The problem of annihilation of galactic clusters and anticlusters arising at the stages of the formation of massive gravitational clusters in the period following recombination of charged particles of the early Universe is also discussed. By the example of spherical macroscopic objects, it is shown that gravitational repulsion between cluster and anticluster results in the impossibility of their annihilation due to the existence of the finite closest approach distance if the latter exceeds the distance between macrosphere centers.