That's a breast on a chip. Why? Because though it looks like a slide, it actually accurately mimics the branching mammary duct system of a breast, where most breast cancers begin. That's key for cancer research since scientists can now test new approaches for treatment, like magnetic nanoparticles. It sounds insane:

The ultimate goal of this project is to introduce magnetic nanoparticles through openings in the nipple, use a magnetic field to guide them through the ducts where they would attach to cancer cells, and then reverse the magnetic field to retract any excess nanoparticles. The nanoparticles could carry contrast agents to improve mammography, fluorescent markers to guide surgeons, or anticancer agents to treat the cancer.

Whatever it takes to save breasts, I'm definitely with it. [PhysOrg]