Contents

14 September 1990
Vol 249, Issue 4974

About The Cover

Thymus from a diabetic rat in which pancreatic islets (light pink clusters) from a foreign strain have been engrafted. The graft caused blood glucose to return to normal. The islets were not rejected, which indicated the immunologically privileged nature of this novel transplant site. The presence of the foreign tissue also induced unresponsiveness to donor strain transplantation antigens. See page 1293 and related news story, page 1248. [Photomicrography by John E. Tomaszewski]