After practicing limited on Thursday, without a helmet for much of it, Terrelle Pryor was cleared per the concussion protocol to return to practice with a helmet along with the rest of his teammates. He had missed Wednesday's practice so he is clearly making the appropriate progress.
He received the concussion near the end of the team's Monday night game versus the Broncos. Matt Flynn took all the reps in drill with the first team receivers in Wednesday's and Thursday's practice and Pryor shared those reps with Flynn according to media present.
It is unlikely at this point Pryor will start just as it has been all week because of his missing Wednesday's practice on a short week. It is also a risky proposition to put him out there now as he would be more likely to receive another concussion if he wasn't completely over the last one.
The NFL will have to clear him on Sunday if he is to play. Even if he doesn't start, there are scenarios in which he could still see some time in the game if he is cleared to play. The Raiders could use him in packages or bring him in the game should Flynn make a lot of mistakes or be ineffective in the early going.
Dennis Allen said he will not name a starter before game time but that's pretty much standard procedure at this point.