There are many hypothesis :
1 – Violation of CPT invariance proposed by A. Sacharow in BB scenario. Experiments with beta mesons shows partial violation of CPT invariance (Ba-BAR, CERN). The “TRAP” experiments found no violations of CPT in cyclotron frequencies with proton-antiproton at the level of 9 parts in 10^11.

2 – No violation CPT invariance.
2.1- There are some antigalaxies in the space – nobody have seen them.
2.2- There is a different gravity – antigravity between antimatter/antimatter and matter/antimatter. Antigravity between antimatter/antimatter and neutral matter/antimatter. Antigravity between antimatter/antimatter and gravity matter/antimatter. Antimatter particles create cosmic voids and different galaxy halos depends on kind of the gravity.

2.3- In Ari-Czeslaw Local Big Bang in Static Total Universe we have whirlwinds of the condensed energy with created matter-antimatter particles in large space.
If the matter goes in other direction as antimatter during creation-annihilation (towards the center of the whirlwind ?) we have a concentration of the matter and antimatter going outside. We have then the wave of the annihilation (sound waves) moving from the center to outsides spheres.
Everything rotate – moving particle fracture the spheres and stretch rotating bars with spiral arms.
One fractioned sphere may create a filament of the galaxy clusters.
The antimatter would be extruded outside of our observable Universe.