Structural signs of dynamic state of synaptic contacts between neurotransplant and brain.

We studied ultrastructure of synaptic connections between long-living dentate fascia transplants and somatosensory area of the neocortex in rats. Giant synaptic terminals of granular neurons upon contact with unusual neuronal targets in the neocortex reproduced their specific constitutive morphological features. At the same time, developing synapses with signs of active structural and metabolic reorganization were revealed. This is indicative of a dynamic state and instability of functional connections between the transplant and brain despite long time after transplantation.