The pigmentarchitectonic divisions and neuronal types of the central nucleus and intercalated masses of the human amygdala.

The central nucleus of the amygdala is a high level limbic center which controls vegetative functions and is involved in neurodegenerative diseases. In the present study, the central nucleus and intercalated masses of the human amygdala have been investigated with the pigment Nissl technique. The central nucleus of the amygdala consists of a main body surrounded by fiber tracts and accessory islands located dorsal to the main body. In the main body, one can distinguish the medial central nucleus with heavily pigmented neuronal types and the lateral central nucleus, which is composed of three subnuclei: the centro-lateral central nucleus has heavily and sparsely pigmented neuronal types, the apico-lateral central nucleus sparsely pigmented neuronal types and the capsular-lateral central nucleus heavily pigmented neuronal types. Based on the pigmentarchitecture, the accessory islands of the central nucleus are part of the apico-lateral and capsular-lateral central nuclei. Altogether, there are eight neuronal types in the medial central nucleus, while four to six neuronal types are found in the subnuclei of the lateral central nucleus. In the intercalated masses, there are four neuronal types, and the predominating cell types are small and sparsely pigmented. In conclusion, the pigment Nissl stain shows that the lateral central nucleus of the human amygdala has three subnuclei, and the accessory islands are part of two of these subnuclei. Furthermore, numerous neuronal types are identified within the central nucleus and intercalated masses of the amygdala, which may reflect the variability in their neurochemical characteristics.