Quintana (thumb) threw a 38-pitch bullpen session Saturday, Jordan Bastian of MLB.com reports.
Quintana underwent thumb surgery back at the start of July. He's been able to throw for over two weeks and is now throwing off a mound, with another similar session scheduled for Monday. He doesn't appear to be too many more bullpen sessions away from returning to game action, though the Cubs have yet to specify exactly when he'll make his season debut.