If neither the A nor B are compatible the result is normal monokarytic mycelium, and if only one of A or B are compatible, the result is either two mycelia growing in opposite directions (only A compatible) or a "flat" phenotype with no mycelia (only B compatible).
If neither A nor B are compatible, the outcome is normal monokaryotic mycelium. If only one of A or B is compatible, the result can be two mycelia growing in opposite directions (if only A is compatible) or a "flat" phenotype with no mycelia (if only B is compatible).