The first experimental evidence for the structure of the Holliday junction came from electron microscopy studies in the late 1970s, where the four-arm structure was clearly visible in images of plasmid and bacteriophage DNA.
A primeira evidencia experimental da estrutura das unións de Holliday procede de estudos de microscopia electrónica feitos ao final da década de 1970, nos que a estrutura de catro brazos era claramente visible en imaxes de ADN de plásmidos e bacteriófagos.