Development coach Stevie Frail has left Celtic, the club has announced.
"I have had a great time at Celtic over the past few years and enjoyed working for a great club with some really good players," he told the Celtic website.
"But I felt the time was right to move on and look at some new challenges in football."
Frail's role will be overseen by professional academy manager Tommy McIntyre until a more permanent appointment is made.
Celtic's head of youth, Chris McCart added: "Stevie has done a great job for the club in recent seasons.
"He has been part of so many of our successes and brought through a lot of talented young players.
"Of course we are sad to see him leave but we wish Stevie very well in all his future ventures."
After a playing career at Dundee, Hearts, Tranmere, St Johnstone and Morton, Frail moved into coaching at Cappielow, then at Hearts in 2004.
He and sporting director Anatoly Korobochka took charge of the first team in 2007-08 following the departure from Tynecastle of Valdas Ivanauskas.