Renowned for his high-fidelity in vivo (inside living organisms) shots of human and other medical subjects, his work details the human birth cycle, from the sperm entering the egg to the final stages of the fully formed human infant. There are other works detailing such processes, but most are based on the scans such as ultrasound and other imaging technologies. Lennart Nilsson’s first book was published in 1965, which contains photographs that are live optical photos captured through endoscopy, which is otherwise used as a medical method for examining, diagnosing and treating the innards of the body.