BRAIN GRAFTS OF CEREBRAL GANGLIA HAVE EFFECTIVENESS IN GROWTH RESTORATION OF DAMAGED HELIX-ASPERSA MESOCEREBRUM

The microsurgical extirpation of the mesocerebrum from the brain of fast-growing juvenile snails (Helix aspersa aspersa: H.a.a) stops their growth. This suggests that neurosecretory cells of the mesocerebrum secrete a growth hormone. Neural grafting has been used as a tool to restore the impaired growth function after mesocerebrum removal in juvenile H.a.a snails. The transplantation of desheathed cerebral ganglia (CG) (i.e. CG with their glioconjunctive outer covering removed), into the place where the mesocerebrum had been re-established growth which depended on the age of the donors. For the grafts of H.a.a CG into H.a.a, it was CG from the youngest donors that restored growth best. However, the CG of adult snails still conserved a slight growth-stimulating activity. Transplantation of the CG from the large, fast-growing sub-species H. aspersa maxima (H.a.m), into the brain of H.a.a with mesocerebrum removed induced faster growth than the H.a.a CG probably because of a more abundant secretion of growth hormone. Our results show that intracerebral CG grafts are well tolerated in snails and that labeling of the neurones of the transplanted CG with a vital fluorescent stain (Fast blue), allowed the observation, over several months, of their integration into the lesion zone of the host brain.