Acetylocholinesterase activity in the nuclei of the amygdaloid complex in the rat.

The amygdaloid complex is composed of nuclei of various cellular structure, different connections and differentiated functions. Delimi-tation of separate amygdaloid nuclei on the basis of cytoarchitectionic or myeloarchitectonic principles exclusively is very often difficult. Therefore it seems, that in addition to purely morphological methods some histochemical techniques have to be elaborated. The methods showing acetylocholinesterase (AChE) activity are especially suitable in this respect (Olivier et al. 1970). It is assumed (see Koelle 1969) that acetylocholine is a transmitter not anly in the peripheral but also in the central nervous system. Therefore , it seems probable, that high AChE activity in some portions of the central nervous system is related to specific functions. have even suggested that in the telencephalon there are separate systems composed of ascending cholinergic neurons and tracts. The results ol previous investigations concerning AChE activity in amygdala of the rat as well as of other animals are contradictory very often due to misleading nomenclature and lack of comparative, histochemical studies of this portion of the brain. So far there is no definite and from the phylogenetic point of view justified subdivision of the amygdaloid complex in the rat. Brodal's (1947) subdivision agrees with our observations only partly. In spite of this we applied it to our work though with far-going modifications taking into account the fact that this nomenclature is in general use.