Originate from a group of rats (probably Wistar strain) brought into Palestine from Liverpool, England by Mr. George Stewart in 1920. This colony was mated with another breed around 1920. The colony was kept at the Mt. Scopus Hebrew University campus as a random bred colony until mid 1948 when it was transferred to the Hebrew University campus in Western Jerusalem. The colony has now been transfered from Hebrew University to Harlan Laboratories. Harlan became Envigo in 2015