Grey's Anatomy 's Ellen Pompeo Reunites with T.R. Knight Following Justin Chambers' Departure

Ellen Pompeo just gave Grey’s Anatomy fans yet another huge dose of nostalgia.

Just one day after the show said farewell to Justin Chambers’ character of Alex Karev, the actress, 50, took to Instagram to share a sweet photo of her and another of the original Grey’s interns: T.R. Knight, who played the beloved Dr. George O’Malley for the long-running show’s first five seasons.

“Old friends are the BEST friends @t.r.knight,” she wrote alongside the photo. “But like we aren’t old … we’ve just known each other for a very long time yes yes that’s it…”

Knight reposted Pompeo’s selfie, adding, “I’m just happy we met when we were fetuses.”

RELATED: How Grey’s Anatomy Addressed Dr. Alex Karev’s Absence in Midseason Premiere After Justin Chambers’ Exit

Knight portrayed the surgical intern for four years before leaving the show in 2009. After deciding to join the Army in season 5, O’Malley was tragically hit by a bus — an accident that eventually killed him. While fans mourned the loss of O’Malley, his continues to be brought up here and there seasons later.

In fact, he was namechecked in Thursday’s farewell to Alex Karev, in his letter to Miranda Bailey.

Scott Garfield/ABC via Getty George O’Malley and Meredith Grey

Earlier Friday, Pompeo thanked fans for their support and to share her thoughts on Karev’s sudden departure after 16 seasons, calling it “the best send off.”

“Hi here I go again,” Pompeo, 50, wrote alongside a video homage to the character. “Thank YOU! You are truly the best most passionate most loyal fans anyone could ever ask for. Because of you we got to make great tv… because of you we got to make television history! I say often life is hard and thank God it is because like I tell my kids… it shows us what we are made …of how strong we really are and let’s face it… without the lows there would be no dancing it out or celebrating this incredible experience we call life. Thanks to our national treasure @therealdebbieallen and the writers for giving Alex Karev the best send off.”

“Thanks to @shondarhimes for creating the most amazing character,” she continued. “For me personally for Karev to go back to the beginning … was the best possible storyline. It pays homage to those incredible first years and the incredible cast … that created a foundation so strong that the show is still standing. So let’s not be sad. As our fearless leader DA always says let’s PULL UP and celebrate the actors the writers and the fantastic crew who make this show come to life every week. No matter what the challenge or how tired we all are in the end … you keep us going … That is worth dancing it out over! So much love and gratitude to you all. Xo E.”

RELATED: The Most Dramatic Grey’s Anatomy Departures

During Thursday’s episode, fans finally got answers as to why Chambers‘ beloved character left Grey Sloan Memorial, his wife Jo (Camilla Luddington) and the home he’s known for 16 seasons.

Alberto E. Rodriguez/Getty Justin Chambers

In four different letters to wife Jo, Meredith Grey (Pompeo), Miranda Bailey (Chandra Wilson) and Richard Webber (James Pickens Jr.), Alex explained that he’d moved to Kansas to be with his ex-wife, Izzie Stevens (Katherine Heigl) and their 5-year-old twins.

RELATED: Grey’s Anatomy Showrunner Bids Justin Chambers’ Character an ‘Impossible Goodbye’

In January, ABC confirmed to PEOPLE that Chambers, 49, was not returning to the franchise.

“There’s no good time to say goodbye to a show and character that’s defined so much of my life for the past 15 years,” Chambers said in a statement to PEOPLE. “For some time now, however, I have hoped to diversify my acting roles and career choices. And, as I turn 50 and am blessed with my remarkable, supportive wife and five wonderful children, now is that time.”

He added, “As I move on from Grey’s Anatomy, I want to thank the ABC family, Shonda Rimes, original cast members Ellen Pompeo, Chandra Wilson and James Pickens, and the rest of the amazing cast and crew, both past and present, and, of course, the fans for an extraordinary ride.”

Grey’s Anatomy airs Thursdays at 9 p.m. on ABC.