How does one go about leaving their body for medical research?

You should investigate places to see exactly where, and to whom, you would like to leave your body. Make sure your loved ones know, and that you have written a will that makes your wishes clear. I recently read a fascinating book called "Stiff: The Curious Lives of Human Cadavers" (or something like that), that described all of the different ways bodies have been useful to science. Before you make a decision, it's worth reading.