Neuronal types in the basolateral amygdaloid nuclei of man.

A parcellation of the human basolateral amygdala is given on the basis of pigmentoarchitectonic analysis. Examination of Golgi preparations and deimpregnated preparations counterstained for lipofuscin pigment revealed three classes of nerve cells: Class I neurons generate a stout main dendrite from one pole of the cell body and several minor ones from the base opposite to the main process. The dendrites are covered with spines. The axon follows a straight course and gives off numerous collaterals. Class I neurons in the lateral and accessory basal nucleus contain finely granulated and widely dispersed pigment. Cells located in the basal nucleus store a large amount of pigment, concentrated at one pole of the cell body. The small class I neurons in the granular nucleus and the intercalated cell masses are marked by large vacuolated pigment granules. Class II neurons have smoothly contoured or sparsely spined dendrites. Size and shape of their cell bodies vary. They contain a large amount of course and intensely stained lipofuscin granules. Class III neurons display similar features in the Golgi preparation but their cell bodies are devoid of pigment. A frequently occurring type is a tiny cell with thin dendrites and profusely branching local axon. Each of the different classes of neurons shows a characteristic pattern of pigmentation. Therefore, Nissl preparations combined with a pigment staining technique, offer the particular advantage of distinguishing the spine-laden neurons from sparsely spined or aspinous types.