Fetal CNS transplants into adult spinal cord: techniques, initial effects, and caveats.
Transplantation of 11 day gestation rat fetal cortex and spinal cord into adult rat thoracic spinal cord is feasible. However, the techniques used at present for the implantation of the fetal transplant result in host spinal gray matter necrosis. One day after implantation the transplant is in a fluid-filled cyst in the host. The transplanted fetal tissue forms spherical neuroepithelia and unorganized cellular arrays. At Day 3 after transplantation the implant has sedimented to the ventral aspects of the fluid-filled cyst. By 10 days, there is an active neuroepithium with differentiating neurons and neuroglia lining the basal portion of the cyst. The transplant then proceeds to fill the cavity formed by host phagocytosis of the debris in the fluid-filled cyst.