Human fetal cerebellar and cortical tissue transplanted to the anterior eye chamber of athymic rats: electrophysiological and structural studies.

Human fetal tissue fragments from cortex cerebri and cerebellum were grafted to the anterior chamber of the eye of adult athymic nude rats. The grafts were obtained from tissue fragments recovered after elective routine abortions, performed in weeks 8-11 of gestation. Both cerebellar and cortex cerebri grafts survived and developed in the anterior chamber of the eye for 1-4 months. The transplants slowly became vascularized from the host iris. The grafts developed blood vessels with laminin-immunoreactive walls and contained relatively high amounts of glial fibrillary acidic protein- and neurofilament-immunoreactivity in the neuropil after 4 months in oculo. Recordings of extracellular action potentials from the grafts revealed spontaneously active neurons with action-potential waveforms similar to those observed in immature rodents. Morphologically, the grafts showed no signs of rejection. Clusters and bands of large neurons resembling Purkinje cells and dense aggregates of smaller granule-like cells could be found in the cerebellar grafts. Large neurons were also seen in the cortex grafts. Taken together, these data suggest that the athymic rat may serve as a useful tool for studies of central nervous system tissue from otherwise immunologically incompatible species.