The Doctor is Immortal-no Regen limit says BBC.

[Mikey]

Being a new Doctor Who fan I'm not overly familiar with the past storylines, how important is the 12 regens to the ongoing mythology of the Who universe? What was the reasoning behind it? Was there some kind of biological or scientific reasoning behind it, or was it a self imposed rule that Time Lords created to keep themselves in check?

If it was the latter, then one could easily just assume that The Doctor no longer has anyone to answer to in that regards so it's not really worth making it into a "thing". Given the fact that the Master has access to additional regenerations in this new series leads me to believe that it a Time Lord restriction rather than a limitation of the biology/technology/science behind the concept of regeneration.

I think it was mentioned for the first time in the Tom Baker story The Deadly Assassin.

It was important to many storylines concerning the Master because he used up all his regenerations and resorted to stealing bodies from the 1970's to 1996.

If the Doctor can just regenerate over and over from now on without any explanation a lot of Classic stories can be thrown out the window including ...

The Deadly Assassin
The Keeper of Traken
Logopolis
Castrovalva
Time-Flight
Mawdryn Undead
The Five Doctors
Planet of Fire
Mark of the Rani
Trial of a Time Lord
Time and the Rani
Survival
Fox TV Movie

to name a few.

[Thor]

I think the change will be explained. After a time the uproar from the classic fans would become too great. I personally think they should use the time lord idea. Meaning that the Timelords placed a limit on how many times one could regenerate. Since they are now gone the Doctor can regenerate as many times as needed.

[samurainoir]

So are regenerations biological/technologically restricted or a self imposed Time Lord restriction?

If it's the latter, then as far as I can discern with my limited Doctor Who knowledge, none of those stories get thrown out the window. Those stories still exist in the relative "past" when the Time Lords were around to restrict regenerations. Now that they are not around, The Doctor does not have to adhere to that 12 regenerations rule. The fact that The Master was "given" (or was it offered? ala 5 Doctors) a new regeneration cycle probably suggests this doesn't it?

Doctor Who mythology is pretty much a moving target over Fifty years of continuity isn't it? He wasn't even declared a time lord until the second regeneration, but that didn't throw away the previous continuity. It just expanded the story. From what I've read, there was even a rather eloquent explanation of how he was part-Human grafted on after the Fox movie with the whole Rassilon/Omega thing.

I think it was mentioned for the first time in the Tom Baker story The Deadly Assassin.

It was important to many storylines concerning the Master because he used up all his regenerations and resorted to stealing bodies from the 1970's to 1996.

If the Doctor can just regenerate over and over from now on without any explanation a lot of Classic stories can be thrown out the window including ...

The Deadly Assassin
The Keeper of Traken
Logopolis
Castrovalva
Time-Flight
Mawdryn Undead
The Five Doctors
Planet of Fire
Mark of the Rani
Trial of a Time Lord
Time and the Rani
Survival
Fox TV Movie

to name a few.

[ODBJBG]

Perfect continuity in a show about time travel is like a fart in the wind. It sounds nice, but it's not particularly easy to track down.

[Meule]

There have been so many changes already. I'm watching the old shows again and I've yet to hear anything about Time Lords. Traveling with the Tardis is like playing jackpot: you never know where you're gonna end up and it's not meant for traveling short distances. The Doctor finds himself in situations that would've been easily fixed in the new series. Do I care that things have changed? No, I enjoy the show for what it is, keeping in mind that it was from the seventies.

[Nostalgiabuff]

I don't care either.....I have been wondering how they planned on getting around the limit since Smith is the eleventh Doctor.

[samurainoir]

So the Doctor is not actually mortal... he has 507 regenerations now.

Looks like Davies is having fun rattling the cages.

[wolfie]

Yes it was 12, now it's 507, well thats that sorted out then.