This review considers the questions of the structural-functional organization of the central nucleus (CN) of the amygdaloid body (AB) of the brain in relation to new data on its involvement in the formation of stress reactions and adaptive behavior in animals. Data are presented on the distribution of neuropeptides, neurotransmitters, and modulators in the CN. It is noted that the CN, appearing at the earliest stages of establishment of the AB, is reorganized with it and reflects the evolution of the whole AB. Detailed data are presented on the cytoarchitectonics of the CN of the AB, its heteromorphousness, and subdivision into zones (subnuclei) based on the use of different study methods and assessment criteria. The neuronal organization of the CN and its subnuclei is considered; detailed descriptions of different types of neurons are provided, with consideration of their topographies, sizes, and shapes and of their perikarya, the orientation and type of branching of their dendrites, the organization of the spine apparatus, and axon structure. The characteristics of the development of the CN of the AB in the ontogenesis of mammals and man are discussed. Analysis of published data and our own results supports the role of the CN not only as an intra-amygdalar integrative center, but also as one of the major channels for the afferent and efferent connections of the AB with the rest of the brain.