A first clue as to the actual complexity of the system of coagulation was the discovery of proaccelerin (initially and later called Factor V) by Paul Owren (1905–1990) in 1947.
A primeira pista da gran complexidade do sistema de coagulación foi o descubrimento da proacelerina (denominada así inicialmente e máis tarde chamada factor V) por Paul Owren en 1947.