Bipolar Planetary Nebulae (hereafter PNe) are almost all of the Type I and have the most massive progenitors among PNe. They are mostly found at very low galactic latitudes and thus are expected to follow rather closely the differential rotation. Moreover since they are strongly suspected to constitute the youngest population among PNe, then some bipolars may have not achieved a complete galactic revolution yet and we can reasonably suppose that some signs of their recent galactic evolution still exist.