Newcastle Falcons loosehead prop Grant Shiells will train with the Scotland squad during the remaining two days of their camp in St Andrews.
The 23-year-old , a former Scotland U20 and U19 internationalist, crossed the border to play for the Falcons in 2009.
"We've invited Grant to train with us given some of the recent injuries we've had on both sides of the front row," said Scotland head coach Andy Robinson.
Scotland team doctor James Robson added: "The Edinburgh props Allan Jacobsen and Geoff Cross are returning to some elements of team training today for the first time since their respective hamstring and concussion injuries.
"Ryan Grant, the Glasgow Warriors prop, sustained a concussive episode against Treviso at the weekend and is currently subject to our graduated return to play protocol."
At this stage, all three are expected to be fit to be considered for selection for Scotland's opening Test against New Zealand one week on Sunday (11 November).
Robson noted that a number of players would undertake only limited training on Tuesday: locks Jim Hamilton (ribs), Al Kellock (back) and Richie Gray (ankle), flanker Ross Rennie (shoulder), fly-halves Ruaridh Jackson (shoulder) and Greig Laidlaw (neck), centre Nick De Luca (ankle) and wing/centre Sean Lamont (facial).