Produced by Shonda Rhimes Grey's Anatomy had all viewers at the edge of their seats for 15 seasons allotting in 317 episodes, making it the second longest scripted primetime show ever on ABC only behind The Adventures of Ozzie and Harriet. But here are 17 things you probably didn't know about the show.

1. "Grey's Anatomy" was going to be called "Complications." But was later changed as a play on the famous medical textbook "Gray's Anatomy," published in 1858.
2. Shonda Rhimes was obsessed with watching surgical shows on the Discovery Channel.
3. "Grey's Anatomy" uses a 'colour-blind' casting technique. This means that each role is cast without the character's race being pre-determined, resulting in a racially diverse ensemble cast and keeping with Shonda Rhimes' vision of diversity.
4. Ellen Pompeo wanted to do a different ABC pilot, written by Bob Orci and Alex Kurtzman, called Secret Service. When that didn't get picked up, she was asked to play Meredith Grey.
5. Ellen Pompeo didn't know Derek was married until the Season 1 finale was being filmed. So she was just as shocked as Meredith to find out he had a wife.

6. Jesse Williams was a teacher before being cast in "Grey's." Imagine Jackson Avery being your actual teacher.

7. James Pickens Jr. got the part of Dr. Richard Webber just minutes after he auditioned. After he read, they asked him to step into the hall, and when they brought him back in, he was offered the part.

8. The character Alex Karev, played by Justin Chambers, was added to the script after the pilot had already been shot, so all of his scenes were digitally implanted into the episode.

9. Kate Walsh was initially hired for only a few episodes, but she had such great chemistry with the cast that she was brought on full time and eventually given her own spin-off, "Private Practice."

10. Unlike her character Lexie Grey who graduated from Harvard Medical School, Chyler Leigh dropped out of high school.

11. Brooke Smith, who played Dr. Erica Hahn (a love interest for Sara Ramirez's Dr. Callie Torres), was let go from the show. She was told the writers could no longer “write for her character."

12. Pompeo got pregnant while filming Season 6, but instead of making Meredith pregnant as well, the writers had the character give part of her liver to her estranged father, Thatcher (Jeff Perry), so that Pompeo could be confined to bed rest to hide her pregnant belly under sheets.

13. When cast members perform a specific medical procedure during an episode, they are given tons of material to understand how it would be done in real life.

14. On set, they used real cow organs and blood matter: red Jell-O, blood and chicken fat.

15. For some of the brain surgeries, lamb brains had to be used.

16. The MRI machine is real.

17. A whole load of "Grey's" characters went on to appear on Shonda's other show, "Scandal." Teddy's husband Henry plays Jake Ballard, Meredith's mum Ellis plays Vice President Sally Langston, and her dad Thatcher is the scheming Cyrus Beene.