The grafted fetal rat pancreas: features of development and rejection.

Pancreata from 17-18-day gestational rat embryos have been transplanted between related and unrelated adult rats rendered diabetic with streptozotocin. In separate experiments allograft recipients were given the immunosuppressive agent cyclosporin A. The morphologic changes in most of these grafts were followed during the first 2 weeks after transplantation. The endocrine, but not the exocrine, tissue developed fully in the isografts and did so at a rate corresponding to that reported for in vitro cultures. Within the allografted pancreata there was no maturation of the exocrine components, and endocrine tissue only reached full maturity if immunosuppression was used. Allograft rejection was similar morphologically to that of other tissues, involving cellular and humoral factors. The cells within the graft evoking rejection were not identified. These studies indicate that if rejection could be adequately suppressed, the endocrine parts of the fetal pancreas would survive and develop.