These are immunofluorescent staining images- antibodies against different proteins are attached to glowing (fluorescent) proteins so we can see them in a microscope. The first photo show an embryonic mouse neural tube, a bunch of cells that will one day become the mouse brain. The second shows a section of mouse placenta. The blue colors the nucleus of the cell and then the red shows a special protein that will make those cells become a certain part of the brain. The while marks proteins found only in a certain type of cells called epithelial cells.