Thursday (Sept. 22) will see "Grey's Anatomy" returning to TV with its 13th season. In the world of primetime television medical dramas, that is no small feat. While it's possible we'll see at least one more season of the Shonda Rhimes drama before it's through, we got to wondering where other popular medical series of this ilk fall on the episode count spectrum.

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'ER' - 15 seasons, 331 episodes

er george clooney noah wyle Greys Anatomy to ER: TVs longest running medical dramas

In 1994, "ER" premiered on NBC and became the longest-running medical drama in American primetime television. Created by Michael Crichton --  yes, the same guy behind "Jurassic Park" and "Westworld" -- the series cemented the careers of actors like George Clooney, Julianna Margulies, Noah Wyle, Anthony Edwards and more.

'M*A*S*H' - 11 seasons, 256 episodes

mash hawkeye Greys Anatomy to ER: TVs longest running medical dramas

Many tend to forget that the 4077's story is indeed a medical drama. Doctors tending to patients during the Korean War gave an interesting spin on the genre. Inspired by the movie of the same name, the show aired from 1972 to 1983.

RELATED: These O.G. ‘Grey’s Anatomy’ characters should return for Season 13

'House' - 8 seasons, 177 episodes

giphy 32 Greys Anatomy to ER: TVs longest running medical dramas

Hugh Laurie was already a well-known actor in the U.K. when he auditioned for the David Shore series, "House, M.D." Inspired by Sir Arthur Conan Doyle's "Sherlock Holmes" stories, Gregory House added a new sardonic flavor to the world of primetime medical dramas, turning the genre on its head for eight solid seasons.

'Quincy M.E.' - 7 seasons, 4 TV movies & 144 episodes

Beginning as four television movies in the fall of 1976, "Quincy M.E." was presented as part of NBC's Sunday Mystery Movie lineup. Starring Jack Klugman ("The Odd Couple"), the 90-minute movies gained in popularity to the point that the network created its own series following the investigations of L.A. County's premiere medical examiner.

Posted by:Aaron Pruner

When he was a child, Aaron memorized the entire television lineup, just for fun. He once played Charlize Theron’s boyfriend in a Japanese car commercial. Aaron’s a lover of burritos and a hater of clowns. TV words to live by: "Strippers do nothing for me, but I will take a free breakfast buffet any time, any place."