This combination of images provided by the Yale School of Medicine in April 2019 shows stained microscope photos of neurons, green; astrocytes, red, and cell nuclei, blue, from a pig brain left untreated for 10 hours after death, left, and another with a specially designed blood substitute pumped through it. (Stefano G. Daniele, Zvonimir Vrselja/Sestan Laboratory/Yale School of Medicine)