 The development of HEVs after prolonged inflammatory stimulus is not restricted to diseased synovium, but can also occur in other tissues, particularly the gut and thyroid.During chronic inflammation of the gut in inflammatory bowel diseases (Crohn's disease and ulcerative colitis) or the thyroid in autoimmune thyroiditis (Graves' disease and Hashimoto's thyroiditis), areas of dense lymphocytic infiltration contain vessels with plump endothelium expressing MECA-79 and HECA-452.These observations suggest that HEVs could play an important role in the pathogenesis of these diseases by mediating abnormal lymphocyte recruitment to the gut or the thyroid.