It's when the Doctor regenerates and so heals himself to stop himself from dying. apparently, in the old, OLD, series (I'm talking years back) the Doctor could only have so many regerations. 13
In 'Journey's End', the Doctor had been wounded by a Dalek and was starting to regenerate. However he used it to just heal himself, and transferred the remaining energy into his severed hand, the one that the Sycorax cut off back in the Series 1 Christmas Special.
Later, as the TARDIS was being destroyed in the Crucible's core, Donna touched the hand, exchanging DNA with it. The hand turned into a human version of the Doctor, while Donna's mind became that of a Time Lord, though it didn't show until later. However during the last scenes there were two Doctors, the human one later went to stay with Rose back in the other dimension.
Doctor Who - 1963 The Three Doctors Episode Two 10-2 is rated/received certificates of: UK:U UK:PG (DVD rating)
The Fifth Doctor debuted at the end of the episode 'Logopolis' and his first proper episode was 'Castrovalva.'
Doctor Who - 1963 The Three Doctors Episode Three 10-3 is rated/received certificates of: UK:U UK:PG (DVD rating)
Doctor Who - 1963 The Three Doctors Episode Four 10-4 is rated/received certificates of: UK:U UK:PG (DVD rating)
Doctor Who - 1963 The Three Doctors Episode One 10-1 is rated/received certificates of: UK:U UK:PG (DVD rating)
February 16th to March 2nd on 1985.
It can be done two different ways. Doctor and Doctor Smith or Doctors Smith can both be used.
160th episode of Doctor Who is in two parts : "Aliens of London"/"World War Three" .
Doctor Who - 1963 The Two Doctors Part Two 22-8 is rated/received certificates of: Australia:G UK:PG
The plural form of the noun doctor is doctors.The plural possessive form is doctors'.Example: The doctors' offices are in building two.
Only time it was seen before the ninth Doctor. Was the seventh Doctor. Sylvester McCoy. He used it in the episode 'Battlefield'. If you watch the episode, and wanto look for it. It is when he enters the UNIT's trailer. He flashes it to the 'new Brigadier'
Doctors - A group of doctors. 'Where are all the doctors?'Doctor's - A possession of the doctor's. 'I picked up the doctor's pen'.Doctor's - Meaning, Doctor is. 'The Doctor's busy right now'.