In the June 25th online edtion of the American J. of Pathology, S. A. Rogers et al. from Washington University School of Medicine reported the results of their study on xenotransplantation of procine islets and pig pancreatic primordia (embryonic day 28) into streptozotocin-treated diabetic rats. The investigators conducted experiments demonstrating normalization of glucose tolerance and without immune suppression. Porcine islets were engrafted into the renal capsule concomitant with pancreatic primordia transplanted into the mesentery. In situ hybridization analysis for porcine X chromosome revealed long-term donor cell engraftement. However, islet engraftment did not occur without transplantation of the E28 pig pancreatic primordia in the mesentery. The authors concluded from their study results that "tolerance induction to a cell component of porcine islets is induced by previous transplantation of E28 pig pancreatic primordia" in an immunocompetent animal.