All three have been vital to Paul Jewell's plans this season, but the manager is not over optimistic about them being available at the Sixfields Stadium.
Dinning missed last Saturday's defeat to Plymouth with a calf strain which also forced him to withdraw at half-time against QPR the previous week.
Jewell rates him as "doubtful" for Friday, and McCulloch is in the same boat.
He was substituted against Plymouth after straining his hamstring, and such injuries can take time to heal.
Top scorer Ellington has been nursing a shoulder injury since the turn of the year – a problem needing surgery in the summer.
He hurt it again in training on Monday, forcing an early withdrawal from the practice ground.
Jewell said: "It's a case of waiting to see how they are later in the week and taking things from there.
"As for the Duke, he has done his shoulder in training – it popped out during Monday's session.
"Fortunately we've got a blank midweek which gives us a bit more time."
If Latics decide not to risk Ellington against Northampton, Andy Liddell will move back up front alongside Neil Roberts with Gary Teale set to come in on the right-wing.
McCulloch's likely replacement on the left side of midfield would be Peter Kennedy, the Northern Ireland international now being free of injury and illness.
Dinning's place in the centre of midfield would again go to Jason Jarrett.
While the injuries continue to stretch the small squad at Jewell's disposal, the schedule of matches is not as busy in the final run-in.
There's an eight-day break between the visit to Northampton and the home game with Brentford.
And the only midweek game left on the fixture list is the Easter Monday derby clash with Oldham AThletic at the JJB Stadium.
Meanwhile, Jewell is confident his side can bounce back from the Plymouth defeat on Friday.
Latics have only lost back-to-back games once this season – in August to Port Vale and Colchester.
Jewell said: "We tend to hit back straight away after a bad result and that shows the character of the players we have here."
Latics reserves were playing Shrewsbury at Robin Park this afternoon in the Avon Insurance League.
Tickets for the Player of the Year presentation on May 3 have sold out.
Article from the Wigan Evening Post.