Ultrastructure of fetal spinal cord and cortex implants into adult rat spinal cord

Abstract

The ultrastructure of cortex and spinal cord from 11-, 12-, and 15-day-old fetuses implanted into the spinal cord of adult rats was studied over 3 months. Under deep Chloropent anesthesia, a 0.5 X 1.0-mm square of fetal cortex or a 1.0-mm segment of fetal spinal cord was implanted subpially between the left dorsal column and the dorsal horn of 70 adult rats. Implants grew toward gray matter, usually interfacing with the host at the isthmus between the horns of the spinal cord. However, implants were observed that occupied the entire left dorsal and ventral horns of the left half of the host spinal cord. Implants had concentric zones: A central zone with basal lamina lined joined channels and subjacent neuroglia; a zone of differentiating implant nervous system; a zone with basal lamina lined implant with overlying pial cells on the dorsal and lateral surfaces of the implant; a zone that interfaced with the host with overlapping neuropil on the lateral and ventral surfaces of the implant. Neuron types were typical for cortical or spinal implants. Implants survived for 3 months and reached stages of neuronal and neuroglial maturation similar to controls. Both fetal spinal cord and brain were successful as implants, had delayed differentiation, and formed complex neuropils. The zone of overlapping interface of the donor and host is an anatomical indication of physiological and functional integration.

Ependyma formation in adult rat spinal cord after transplantation of fetal cerebral cortex homografts

“…These cell aggregates formed rosettes or epithelial ovoids [Bernstein et al, 1984a, 1984b: Freed, 1983. The epithelial ovoids appeared to be centers for cell division [Bernstein et al, 19851 and indicate continued growth of the graft by cell division.…”

“…The cysts in which the transplants are located appear to be lined with ependymal cells [Bernstein et al, 1984a[Bernstein et al, , 1984b.…”

“…The cell types of brain grafts have been characterized by fluorescence Freed, 1983;Perlow et al, 19791 and electron microscopy [Kromer, 1981;McLoon and Lund, 19831. Spinal cord grafts have been characterized by the same methodologies [Bernstein et al, 1984a[Bernstein et al, , 1984bBernstein, 1986, 1986a;Bunge et al, 1983;Das, 1983;Nornes et al, 1983Nornes et al, , 1984Pate1 andBernstein, 19831. Recently, immunohistochemistry [Connor andBernstein, 1986, 1986a;Ebner et al, 1984;Sladek and Gash, 19841 and receptor chemistry [Moody et al, 19861 have also been utilized to characterize the subpopulations of cells that are expressed in fetal CNS grafts to the adult nervous system.…”

Delayed transplantation of foetal cerebral tissue into injured spinal cord of adult rats

“…stances, we have found no sign of morphological differentiation to pyramidal neurons. On the basis of the observations of Bernstein et al 3 and other authors 4'28,37'4~ it may be hypothesized that the failure of these neurons differentiate to more mature stages is due to the fact that they receive a lower number of synaptic afferents. This assumption, on the other hand, would support our interpretation in that, within the transplanted tissue, when it survives in the form of a compact tissue block, there exist the necessary circumstances for maturation, not merely for a correct syn-…”

Fetal CNS Transplants into Adult Spinal Cord: Techniques, Initial Effects, and Caveats

“…'37"41' The fetal spinal cord and cortical transplants in thoracic spinal cord survived for the duration of the experiments (up to 6 months to date), and both had a characteristic Veterans Administration Medical Center and Departments of Neurosurgery and Physiology, George Washington University School of Medicine, Washington, DC. 39 growth pattern. There are three concentric zones in the graft.…”