Before there was plastic surgery and photoshop, the stars kept up an illusion of glamorous perfection without resorting to knives, needles, or software. How did they do it? The answer is the Big Five: RKO, Warner Brothers, 20th Century Fox, MGM, and Paramount Pictures.
During the Golden Age of Hollywood, the studio system owned the stars, who were literally created and exploited to suit a studio's needs. Actors and actresses were contract players bound up in 5-7 year contracts to a single studio, and could be loaned out to other film companies at any time. It wasn't even until 1945 that stars gained a legal right to freelance. (Quick: who was the last contract player signed? Jamie Lee Curtis in 1977!)