In Angiosperms pollen tube liberates its male gametes into the : -

The pollen tube grows through the style and enters the ovule through the micropyle.
Guided by the filiform apparatus of the synergids, it enters one of the synergids and releases its two male gametes into the cytoplasm of that synergid.
From there, one male gamete moves to the egg (syngamy) and the other to the central cell (triple fusion).
So the pollen tube liberates its male gametes into the synergids.