Six Nations: Jonathan Sexton in Ireland squad against Italy

Jonathan Sexton has not played since being concussed in Ireland's win over Australia on 22 November

Fly-half Jonathan Sexton is in Ireland's opening Six Nations squad but could be ruled out of the first match against Italy due to concussion.

Ireland play in Rome on 7 February but the Racing Metro player's current stand-down period is until 14 February - the day Ireland face France.

Cian Healy and Sean O'Brien are named even though they have yet to return to action after lengthy injury absences.

The 46-man squad includes uncapped pair Nathan White and Jack Conan.

New Zealand-born Connacht prop White looked set to make his Ireland debut in the autumn internationals before being ruled out of all three games because of an arm injury.

Back row Conan earns his call-up after producing impressive form for Leinster in recent weeks.

The extended squad has been named for the two opening Six Nations matches and Ireland Wolfhounds's game against England Saxons in Cork on 30 January.

Sean O'Brien and Cian Healy are both nearing returns to fitness after long injury absences

With Healy and O'Brien not featuring in Leinster's final European Champions Cup pool match against Wasps on Saturday, they both could make their return to action after more than four months out in the Wolfhounds game.

Flanker O'Brien has not played since the start of the season after suffering a recurrence of a shoulder problem while Healy has been ruled out by a serious hamstring tear.

Sexton has been out since sustaining concussion in Ireland's win over Australia on 22 November.

French rugby medical authorities then stood down Sexton for 12 weeks which, as it stands, will rule him out of Ireland's opener in Rome.

Injured Ulster trio Paddy Jackson, Stuart Olding and Dan Tuohy will miss the entire Six Nations but the 46-man squad does include their provincial team-mates Rory Best, Tommy Bowe, Jared Payne, Iain Henderson, Robbie Diack, Rob Herring, Craig Gilroy and Darren Cave.

Ulster wing Andrew Trimble is among a number of players who will remain with their provinces to continue their recovery after injury.

Another Ulster man, Luke Marshall, is also in this category along with Munster trio Donnacha Ryan, Robin Copeland and David Kilcoyne.

Regular scrum-half Conor Murray [neck] and Robbie Henshaw [ankle] are both included despite being troubled by injury.

Ulster flanker Chris Henry will miss the entire Six Nations following his heart surgery before Christmas while Munster front row Damien Varley has also been ruled out.

Ireland 46-man squad

Forwards: Michael Bent (Leinster), Rory Best (Ulster), Jack Conan (Leinster), Sean Cronin (Leinster), James Cronin (Munster), Robbie Diack (Ulster), Dave Foley (Munster), Cian Healy (Leinster), Jamie Heaslip (Leinster), Iain Henderson (Ulster), Rob Herring (Ulster), Mike McCarthy (Leinster), Jack McGrath (Leinster), Marty Moore (Leinster), Jordi Murphy (Leinster), Sean O'Brien (Leinster), Paul O'Connell (Munster), Tommy O'Donnell (Munster), Peter O'Mahony (Munster), Mike Ross (Leinster), Rhys Ruddock (Leinster), Dominic Ryan (Leinster), Richardt Strauss (Leinster), Devin Toner (Leinster), Nathan White (Connacht

Backs: Isaac Boss (Leinster), Tommy Bowe (Ulster), Darren Cave (Ulster), Gordon D'Arcy (Leinster), Keith Earls (Munster), Luke Fitzgerald (Leinster), Craig Gilroy (Ulster), Robbie Henshaw (Connacht), Felix Jones (Munster), Dave Kearney (Leinster), Rob Kearney (Leinster), Ian Keatley (Munster), Ian Madigan (Leinster), Kieran Marmion (Connacht), Fergus McFadden (Leinster), Conor Murray (Munster), Jared Payne (Ulster), Eoin Reddan (Leinster), Noel Reid (Leinster), Jonathan Sexton (Racing Metro 92), Simon Zebo (Munster)