150$ ms. Small scale inhomogeneities (colored as red or yellow) are seen, which predominantly comes from neutrino-driven convection and anisotropies of the accretion flow, but the shape of the gain region is very close to be spherical before the onset of an explosion. This suggests that the bipolar geometry of the shock is produced not by the global anisotropy of the neutrino heating in the vicinity of the neutrino sphere, but by multi-D effects such as by neutrino-driven convection and the SASI in the gain regions after the explosion (gradually) sets in.

Reflecting the stochastic nature of the multi-D neutrino-driven explosions, the blast morphology changes from models to models. The left and middle panels of Figure \[fig2\] show that a stronger explosion is obtained toward the north direction (model 3D-H-2) and the south pole (model 3D-H-3), which is only different from model 3D-H-1 (e.g., Table 1) in terms of the imposed initial random perturbations. Note that due to the use of the spherical coordinates, we cannot omit the possibility that the polar axis still gives a special direction in our 3D simulations. But more importantly, our results show that the final fate of the 3D and 2D models whether an 