Courteney Cox wishes her BFF Jennifer Aniston a happy 52nd birthday

Courteney Cox joined the chorus of stars sending their love to Jennifer Aniston as the actress celebrated her 52nd birthday on Thursday.

The pair have become thick as thieves ever since starring together on the hit series Friends, and their enduring friendship was put on show as Courteney posted a gushing tribute to the birthday girl on her Instagram account.

‘Happy Birthday Jenny Louise! We’ve known each other so long I don’t even remember why I call you that. I love you!’ Courteney, 56, captioned the photo, along with two heart emojis.

Birthday girl! Courteney Cox was among the many stars sending their love to Jennifer Aniston as the actress celebrated her 52nd birthday on Thursday

The slideshow included a photo of the women snuggling beside Courteney’s young daughter Coco, who slumbered with a finger in her mouth.

The second photo was a flashback of the two women sitting next to each other inside an airplane.

Jennifer beamed with joy as she rested her head against Courteney’s cowboy hat

Jennifer was really feeling the love on Thursday as she marked another year around the sun.

'I love you!' The slideshow included a photo of the women snuggling beside Courteney's young daughter Coco, who slumbered with a finger in her mouth

‘I love you!’ The slideshow included a photo of the women snuggling beside Courteney’s young daughter Coco, who slumbered with a finger in her mouth

The actress was sent well-wishes from her ex-husband Justin Theroux, followed by her Morning Show co-star Reese Witherspoon. 

‘Happy birthday to my sweet friend,’ wrote 44-year-old Reese who played Jennifer’s younger sister on the long-running sitcom Friends.

In the Instagram image Jennifer has on a black pantsuit and Reese models a skirt suit with heels.

So close! Jennifer Aniston turned 52-years-old on Thursday and her Morning Show co-star Reese Wtherspoon made a post

So close! Jennifer Aniston turned 52-years-old on Thursday and her Morning Show co-star Reese Wtherspoon made a post

They appear to be on set for their Apple+ series The Morning Show as they both give a thumb’s up.

‘Happy birthday to my #morningshow co-host!’ began the Emmy nominee.

‘From Green sisters to news anchors, we always manage to find time to talk and laugh about every topic under the sun.’

The Oscar winner then added: ‘Just one of the many reasons why I feel so lucky to know you on and off the screen. Celebrating you today, my hysterical / loving / talented friend! @jenniferaniston✨.’

Friends forever: 'Happy birthday to my sweet friend,' wrote 44-year-old Reese who played Jennifer's younger sister on the long-running sitcom Friends

Friends forever: ‘Happy birthday to my sweet friend,’ wrote 44-year-old Reese who played Jennifer’s younger sister on the long-running sitcom Friends

In another photo, Reese is leaning on Jennifer as she wears a pinstriped pantsuit and holds a glass of lemon water.

‘Happy birthday my sweet friend!’ wrote the Big Little Lies star.

‘What a joy to laugh and create with my partner/sister/friend everyday!’ added the power producer. 

Reese has produced not only The Morning Show but also Big Little Lies and Little Fires Everywhere under her Hello Sunshine banner.

Good wishes: In the Instagram image Jennifer has on a black pantsuit and Reese models a skirt suit with heels. They appear to be on set for their Apple+ series The Morning Show as they both give a thumb's up

Good wishes: In the Instagram image Jennifer has on a black pantsuit and Reese models a skirt suit with heels. They appear to be on set for their Apple+ series The Morning Show as they both give a thumb’s up

Meanwhile, Jen’s ex Justin made quite the splash on Thursday morning.

He said he loved Jen: ‘[heart you B!’ 

It is not known why The Leftovers star often calls her B as the letter is not in her initials – her middle name is Joanna.

All that sweet affection: Justin Theroux wished a happy 52nd birthday to his ex-wife Aniston on Thursday

All that sweet affection: Justin Theroux wished a happy 52nd birthday to his ex-wife Aniston on Thursday

The pair were married from 2015 until 2017 but managed to stay friendly after what Justin has previously called a ‘gentle separation.’

The Friends icon threw a glance over one shoulder as she climbed the stairs while modeling a long flowing overcoat.

They announced their split in February 2018 and a few months later Justin told the New York Times about how amicable the process had been.

‘The good news is that was probably the most – I’m choosing my words really carefully – it was kind of the most gentle separation, in that there was no animosity.’ 

The Tropic Thunder writer added: ‘In a weird way, just sort of navigating the inevitable perception of it is the exhausting part.’

The way they were: The pair were married from 2015 until 2017 but managed to stay friendly after what Justin has previously called a 'gentle separation'; pictured in 2015

The way they were: The pair were married from 2015 until 2017 but managed to stay friendly after what Justin has previously called a ‘gentle separation’; pictured in 2015

Justin, who is three years younger than Jennifer, married her in Bel-Air in 2015 and they broke up about two years later.

Justin and Jennifer began dating in 2011, having worked together on the film Wanderlust. He had carried on a 14-year relationship with costume designer Heidi Bivens that collapsed in 2011. 

At the time, E! News claimed that Heidi had been, according to a friend of hers, ‘”straight-up dumped,”‘ though the report qualified: ‘Not to say it’s Aniston’s fault, maybe the timing was just terrible?’

‘Things were already over between him and Heidi before he got close to Jen,’ a source in Justin’s camp insisted to Page Six

As seen in 2001: Last year the public saw how much Jennifer's relations have thawed with her first husband Brad Pitt who infamously left her for Angelina Jolie in 2005

As seen in 2001: Last year the public saw how much Jennifer’s relations have thawed with her first husband Brad Pitt who infamously left her for Angelina Jolie in 2005

Heidi’s mother Marilyn spoke to Radar Online in 2016, claiming that Justin initially tried to persuade Heidi he and Jennifer were not an item.

Marilyn said: ‘Heidi told me what Justin had told her, that something was going to be written about him and Jennifer, that something was going on between them and he wanted her to know that it was nothing, there was nothing to it.’

Ultimately, Heidi discovered the rumors were true, ‘And my sweet Heidi she calls me and says: “Oh mommy.” I was going through cancer at the time. It was a time that hurt our family.’ Marilyn recalled.

Last year the public saw how much Jennifer’s relations have thawed with her first husband Brad Pitt who infamously left her for Angelina Jolie in 2005.

So sweet: Jennifer was seen having a friendly conversation backstage at last year's SAG Awards with her first husband Brad Pitt

So sweet: Jennifer was seen having a friendly conversation backstage at last year’s SAG Awards with her first husband Brad Pitt

Brad and Jennifer both won acting trophies last January at the SAG Awards – where he made a joke onstage about his failed marriages.

He vamped sarcastically that it had been ‘difficult’ to play a ‘guy who gets high, takes his shirt off and doesn’t get on with his wife’ in Once Upon A Time In Hollywood. 

The camera then cut to the audience where his Jennifer clapped at the joke and wore an expression of wry recognition.

She and Brad were spotted having a friendly conversation backstage – and as she walked away she placed a hand on his chest and he briefly held onto her wrist.