Hieronymus Fabricius ab Aquapendente (1537-1619), Italian anatomist. Also known as Hieronymus Fabrizio, he made a major study of the venous system and was the first to describe the valves in the veins. He did not realise their true role though, believing that they were meant to impede blood flow in order to allow surrounding tissue to absorb nutrients. Fabricius' work greatly influenced William Harvey, who was one of his students. Fabricius also studied the development of the chick embryo. His description of the development of the foetus contains many errors but had the effect of lifting embryology into an independent science.