Henry and Fitzpatrick were in the match day squad for Ireland's defeat to England at the Aviva Stadium on Sunday.
Prop John Afoa is also named in Mark Anscombe's 25 man panel following a short stint in New Zealand. Half backs Michael Heaney and Paddy Jackson have also been added to the squad.
Ulster remain top of the PRO12 table despite the 12-16 home defeat to Ospreys at the weekend. They have a seven point advantage over second places Glasgow Warriors going into the round 15 matches.
Extended Ulster squad v Zebre, RaboDirect PRO12, Friday 15th February, Ravenhill, 7.05pm;
Forwards (14)
Rob Herring, Niall Annett, Tom Court, Callum Black, John Afoa, Declan Fitzpatrick, Johann Muller, Neil McComb, Lewis Stevenson, Dan Tuohy, Chris Henry, Iain Henderson, Mike McComish, Robbie Diack.
Backs (11)
Ruan Pienaar, Michael Heaney, Stuart Olding, Paddy Jackson, Paddy Wallace, Luke Marshall, Darren Cave, Michael Allen, Andrew Trimble, Chris Cochrane, Ricky Andrew.
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland