French defender Deslandes, 20, has played eight times for Wanderers, while Republic of Ireland youth midfielder Ronan, 19, has featured 13 times for the Championship high-flyers – three times in the league this season.
Boss Kenny Jackett told Pompey’s website: “We’re short on natural players at the back currently, so Sylvain can hopefully help us continue our excellent defensive record this season.
“I worked with both of them during my time at Wolves and I’m pleased to link up with them once again.”
Chelsea defender Andreas Christensen has revealed that he sought advice from club legend John Terry after making a few costly mistakes recently.
Nemanja Matic believes Manchester United boss Jose Mourinho's driven methods and high expectations will bring the club more success.