This negative stained transmission electron micrograph (TEM) shows recreated 1918 influenza virions that were collected from supernatants of 1918-infected Madin-Darby Canine Kidney (MDCK) cells cultures 18 hours after infection. To separate these virions, the MDCK cells are spun down (centrifugation), and the 1918 virus in the fluid is immediately fixed for negative staining. The solid mass in lower center contains MDCK cell debris that did not spin down during the procedure. Dr. Terrence Tumpey