Leonard Hayflick's inverted microscope from the late 1950s laid the foundation for virtually all microscopes in cell culture labs, notes Terry Sharrer here. Hayflick, currently professor of anatomy at the University of California at San Francisco School of Medicine, came up with "the Hayflick limit" - the number of times a cell can divide before dying - and developed a cell line that has since been used to develop many childhood vaccines. Hayflick's interest in cell mortality made him a perfect contributor to this month's feature on redesigning humans to withstand aging (see article here). "It's a kind of fantasy," he says, but warns that unless we can understand the fundamental principles of aging, and not age-related disease, the whole exercise is "futile."