Passed along by Afrooz (thanks!).
While many people have heard of sex reassignment/corrective surgery (i.e., surgically changing someone's genitals to match their experienced sex), most have no idea of what the surgery involves. It's a tricky process, and one that is constantly being refined to produce more optimal results for the patient in terms of both appearance and functioning.
Surgery typically follows after sex hormone therapy has begun. Sex hormones are required for the person's lifetime. For someone who transitions physiologically from male to female, female sex hormones are necessary as the body does not produce its own, even after surgery (i.e., we're not at a point where ovaries, which are the primary source of female sex hormones, can be transplanted).
The video below depicts the surgical procedure required for transition from male to female. Keep in mind that it was produced in 2009, and there have been major advancements since. Nonetheless, it gives you a good idea of how complicated the procedure can be.