Fifty years ago on this day, Amitabh Bachchan made his Bollywood debut with KA Abbas' "Saat Hindustani". On Thursday, son Abhishek Bachchan penned a heartfelt note to celebrate the occasion.

Taking to social media, Abhishek wrote, "Not just as a son, but as an actor and a fan... We are all blessed to witness greatness! There is so much to admire, to learn and even more to appreciate. Several generations of cinema lovers get to say we lived in the times of BACHCHAN!!! Congratulations Pa on completing 50 years in the Film industry. We now await the next 50! Love you. Amitabh Bachchan #50yrsofSaatHindustaani #50yrsofBachchan #GiveItUpForBachchan."

Reacting to Abhishek's tweet, Karan Johar wrote: "He will remain the most inspiring story in the world of entertainment! Words alone cannot describe his achievements...we are all honoured to be able to watch his genius unravel in front of our eyes! Congratulations to the proud son".

Ekta Kapoor commented, "There are stars ...then superstars ...and then there is AMITABH BACHCHAN (uncle /sir)".

Actress Divya Dutta reacted, "Yesss!! We are super lucky to have lived in the times of Bachchan! And even luckier to have known him personally and shared screen space with him!! How much we love you sir @SrBachchan!!! Happy 50 years sire and many many more!!! You are t reason many of us love being in films!"

Written and directed by Khwaja Ahmad Abbas, "Saat Hindustani" was released on November 7, 1969. The film marked Amitabh Bachchan's debut in Bollywood. This was followed by classics like "Anand", "Bombay to Goa", "Zanjeer", "Abhimaan" and "Namak Haram" in his initial few years.

On the work front, the megastar who currently hosts the popular quiz show "Kaun Banega Crorepati", has his kitty full with the movies "Bhramastra", "Chehere", "Gulabo Sitabo" and "Jhund".