Antimatter in Different Baryogenesis Scenarios
  Possible mechanisms of abundant creation of antimatter in the universe are reviewed. The necessary conditions for that are: baryonic charge nonconservation, spontaneous breaking of charge symmetry or nonequilibrium initial state, and the formation of appropriate initial conditions during inflation. In this case the universe may be populated with domains, cells, or even stellar size objects consisting of antimatter. 
A.D. Dolgov