Credit: Eric McCandless/Getty Images Photo: Season 7: These Arms of Mine
Lily Price was going to die if the docs didn't remove the tumor on her trachea, but she was going to die if they did. Luckily for her, Arizona doesn't believe in a no-win scenario. Arizona's bold idea was to build a whole new trachea for Lily from scratch. But such a thing really possible?

Yes indeed. And in fact, regenerated tracheas are crucial because, as Grey's consultant Meg Marinis explains, neither artificial nor donor tracheas have proven to be successful. Technically, the correct plural form of trachea is tracheae, but that just looks whack to us. Ahem. As we were saying, to create new tracheas, real-life doctors do pretty much what fake-life Alex did. They take cartilage cells and fibrous tissue from the patient's rib and then turn it into a protein liquid. After that, they let that liquid soak into what is known as "scaffolding" and then sculpt it into the shape of a tube. That tube is incubated for roughly a week and then implanted into the patient's body to fully mature. (Lily's was placed in her abdomen.) And then after a couple months, the trachea is put in place in its new home, replacing the malfunctioning one.

This type of tissue regeneration is becoming more and more commonplace, and it's not just for tracheas; doctors also do similar processes to replace bone, cartilage, and heart valves. As Marinis explains, more complicated tissues are harder to recreate, but scientific progress keeps churning. Who knows what docs might be able to replicate next?