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

It is known that a histocompatibility system is not developed to the same e xtent in lower invertebrates as in vertebrate animals. We assumed that the xenografts from the newborn invertebrate nervous system would not exert des tructive effects on the brain of the vertebrate recipient even without immu nosuppressive therapy. In search of brain xenografts (XG) capable to surviv e in the brain of a recipient without intensive immunosuppression, we trans planted ganglia of terrestrial snails into the rat brain. We compared effec ts of transplantation of the XG taken from anterior brain of the 18-day emb ryo chicken (XGC) and from ganglia of a newborn terrestrial pulmonate snail (Helix aspersa L., XGSn). Part of the XGSn were stained by vital fluoresce nt dyes Bisbenzimid or Fast Blue before grafting. The XGSn were implanted i nto the neocortex. parenchyma in each hemisphere. Rat brains with the XGC w ere examined 5 days after, and brains with the XGSn - 5 and 28 days after t he transplantation. Nonstained sections with the XGSn labeled with fluoresc ent dyes prior to transplantation were investigated in fluorescent microsco pe and stained later with tionin and cresyl-violet. Quantitative videoimage analysis of lymphocyte aggregations, reactive gliosis, morphology of the X G areas, and implantation trace was performed. It was found that the XGSn t ransplantation did not elicit in the rat brain an intensive immunological c onflict 5 and 28 days after transplantation. In contrast, the XGC rapidly e licited 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 s nail tissue transplantation serving the humoral integration of the XG and t he host brain. Migration of molluscan glial cells was observed in the brain of recipients, (C) 2001 Elsevier Science BY. All rights reserved.