Cytoarchitecture of the nucleus of the lateral olfactory tract: a Golgi study in the rat.

Examination of Golgi-impregnated rat brains reveals that three main cell types can be distinguished in the nucleus of the lateral olfactory tract (NLOT). Class A neurons, by far the predominant cell type seen in NLOT, are spiny projection neurons that differ in form and orientation in each of the three layers of the nucleus. In layer I, the superficial plexiform layer, and in layer III, the deepest layer of NLOT, most class A neurons have a stellate or semi-pyramidal shape. In layer II, the intermediate layer of NLOT, class A neurons are pyramidal cells that have one or two apical dendrites that extend ventrally through layers II and I, and numerous basal dendrites which arborize in the vicinity of the cell. Axons of class A neurons in layers II and III are directed towards the commissural bundle of the stria terminalis and emit collaterals that appear to arborize in the layer of origin. Class B neurons are spine-sparse stellate cells that are found in all three layers of NLOT. Their axons, when well-impregnated, are seen to form dense local arborizations in the vicinity of the cell. Class C neurons, which have been observed only in layer III, are small neurogliaform cells with numerous, short, varicose dendrites that branch profusely. Axons branch several times in the vicinity of the cell.