Human Ear + Mouse = Creepy + Cool

A few weeks ago, I mentioned in class that scientists were able to insert a segment of human DNA into a mouse genome in order to produce a human ear. Okay, I lied...scientists did not insert the ear gene (a rather stupid assertion on my part, because it's unlikely the ear is coded by just one gene -- it probably takes several genes to code for an ear, making it a polygenic trait), but actual cartilage cells. Cartilage is the squishy connective tissue that makes up your ears and nose. The cells underwent mitosis (cell division) inside of a mold to form the ear. There's a cool picture of the mouse in this article on the BBC Web site (Warning: not for the squeamish!). For a more complete explanation of this process, check out this post at madsci.org.