[The reaction of the neocortical structures in the seal Pusa sibirica to a prolonged stay under water].

Using light and electron microscopic techniques, structural and functional changes in the neurones and glia of the Baikal seal neocortex were revealed during diving. These changes include shifts in tinctorial properties of cells, in the number of dendritic spines, cell ultrastructure (condensation and redistribution of nuclear chromatin, swelling of organoids, etc.). These changes are both non-specific and reversible, indicating high reserve capacities of the brain in this species.