on example of wild and hatchery ( cultivated in ponds and pools ) young russian sturgeons and white salmons , it is shown that fishes cultivated in more complicated ecological conditions ( in natural reservoir in comparison to artificial and in ponds in comparison to pools ) have greater sizes of cns structures connected with the development of the analyzer leading in the life of this species ( the midbrain -- in white salmon , the forebrain -- in sturgeon ) and are characterized by a higher content of dna in the brain and of rna at the unit of dna .
C0085140
forebrain
C0006104
brain