I review recent results from our deep ROSAT and Chandra observations of two galaxies , M101 and NGC 4631 , in fields of exceptionally low Galactic extinction .
Large amounts of X-ray-emitting gas are detected in these galaxies .
Such gas is produced primarily in massive star forming regions and have an average characteristic temperature of a few times 10 ^ { 6 } K. Cooler gas ( \sim 10 ^ { 6 } K ) is found typically outside galactic disks and may represent outflows from blown-out superbubbles .
Propagation of star formation , driven by the expansion of hot gas , appears to be operating in giant HII complexes .
A substantial fraction of photo-evaporated gas in such complexes may be mass-loaded into hot gas , which explains their large X-ray luminosities .
These processes likely play an important role in determining the global properties of the interstellar medium , especially the disk/halo interaction .