Comparison of reactive processes in the rat brain elicited by xenotransplantation of nervous tissues of chicken or pulmonate snail

Abstract

It is known that a histocompatibility system is not developed to the same extent in lower invertebrates as in vertebrate animals. We assumed that the xenografts from the newborn invertebrate nervous system would not exert destructive effects on the brain of the vertebrate recipient even without immunosuppressive therapy. In search of brain xenografts (XG) capable to survive in the brain of a recipient without intensive immunosuppression, we transplanted ganglia of terrestrial snails into the rat brain. We compared effects of transplantation of the XG taken from anterior brain of the 18-day embryo chicken (XGC) and from ganglia of a newborn terrestrial pulmonate snail ( Helix aspersa L., XGSn). Part of the XGSn were stained by vital fluorescent dyes Bisbenzimid or Fast Blue before grafting. The XGSn were implanted into the neocortex parenchyma in each hemisphere. Rat brains with the XGC were examined 5 days after, and brains with the XGSn – 5 and 28 days after the transplantation. Nonstained sections with the XGSn labeled with fluorescent dyes prior to transplantation were investigated in fluorescent microscope and stained later with tionin and cresyl-violet. Quantitative videoimage analysis of lymphocyte aggregations, reactive gliosis, morphology of the XG areas, and implantation trace was performed. It was found that the XGSn transplantation did not elicit in the rat brain an intensive immunological conflict 5 and 28 days after transplantation. In contrast, the XGC rapidly elicited a strong immune response resulting in massive obliterations in the rat brain and were rejected in 5 days. Labeled snail glia and vessels were observed in the stained XGSn 28 days after transplantation by fluorescence imaging. Putative snail vessels grew into the rat brain from the place of snail tissue transplantation serving the humoral integration of the XG and the host brain. Migration of molluscan glial cells was observed in the brain of recipients.