Golgi studies on the amygdaloid nuclei of the cat.

The amygdaloid complex was studied in the cat in Golgi-Kopsch stained section series. Golgi type I (or long axon) neurons are present in all the amygdaloid nuclei. They vary in the different nuclei in shape, arrangement and in size but all have axons that leave the amygdala to establish connections with other regions. They usually have one or more initial locally arborizing collaterals. Two types of interneurons with short axons (Golgi type II) can be distinguished especially in the basal, lateral, cortical nuclei and in the amygdaloid area. One type has an axon arborizing by repeated dichotomical ramifications or in a fountain-like manner, but it does not extend beyond the span of the dendritic tree. The other type has more the character of the neurogliform cells with extremely delicate, beaded processes, the axon and dendrites cannot be easily distinguished. A third type of interneurons was observed in the lateral and basal nuclei. This type of interneurons has a longer axon, which divides into two branches, one arborizes in the neighborhood of the cell body, the other passes on for a further distance to terminate in other nuclei of the complex. The classification of this cell type, hence, is a matter of argument. The intraamygdaloid course of fibers associated with the stria terminalis was studied. The terminal arborizations of the afferent component were observed in the cortical and basolateral nuclei, the afferent component of the stria originates from cells in the central, cortical and medial nuclei. A reciprocal connection between the preamygdaloid part of the piriform cortical areas and the ventrolateral part of the amygdala could be ascertained. Terminal arborizations of some of these cortical afferents were observed in the basolateral nuclei.