[External acetylcholinesterase in different brain regions of a number of vertebrates].
In different parts of the brain (forebrain, midbrain, mesencephalon, nucleus caudatus, cerebellum and medula oblongata) parallel studies have been made on the total activity of AChE in homogenates and the activity of external AChE in slices. It was shown that the share of the external AChE in all brain structures decreases from Cyclostomes to Mammals. The most significant decrease was found in the forebrain. Within the same species (albino rats), phylogentically young brain structures (forebrain) contain smaller amounts of the external AChE, as compared to phylogenetically more ancient ones.