Abstract
Organ-cultured foetal mouse pancreatic islets can reverse streptozotocininduced diabetes in syngeneic mice. Tissue from one donor is enough to produce and maintain euglycaemia in each recipient, but even smaller amounts of donor tissue may be sufficient and less than one third of a foetal pancreas frequently suffices. Insulin extracted from grafts removed after some months in situ shows that their insulin content is proportional to the amount of tissue transplanted, and suggests that the grafted foetal islets have a finite capacity for growth. In organ culture some loss of potential islet tissue may occur, and larger grafts are obtained when small pieces of tissue are cultured, thereby minimizing losses of tissue in vitro. The growth of the graft in situ also depends on the diabetic state of the host, and greater and more prolonged mitotic activity is seen in grafts in diabetic than in non-diabetic recipients, A degree of hyperglycaemia in the recipient may enhance graft growth.