She plays a steel-nerved forensics investigator on CSI, but Jorja Fox still gets squeamish recalling her anatomy class at Melbourne (Fla.) High School. “It required dissecting. When the cats arrived, I asked for a pregnant one,” says Fox, 34. “I thought I was really rugged, but by week’s end, I could barely stay in class.” Fortunately for Fox, the atmosphere on the CSI set isn’t particularly grim. “We shot a scene with an actress who was strapped on a gurney and couldn’t move,” says Fox. “[William Petersen] and I started tickling her. The victims really have to watch out for us.”