The neuronal structure of the medial geniculate body in the pig--Nissi and Golgi study.

The studies were carried out on the brains of adult pigs. The preparations were made by means of the Golgi technique as well as the Nissl and Klüver-Barrera methods. Four types of neurons were described in the medial geniculate body (MGB) of the pig: 1. Multipolar neurons (perikarya 30-45 microm) with rounded, oval or quadrangular perikarya from which arise 4-7 dendritic trunks. The dendrites divide dichotomically twice, may send out collaterals and give off ramifications. The dendritic branches possess varicosities and knob-like spines. These neurons predominate in MGB. 2. Pear-shaped neurons (20-35 microm) with one or two dendritic trunks arising from one pole of the cell body. These dendrites have a tufted appearance. 3. Triangular neurons (30-45 microm) possess three thick dendrites which first bifurcate near the soma and then divide profusely into daughter branches. 4. Fusiform neurons (30-50 microm) have usually two dendritic trunks which arise from the opposite poles of the cell body and divide dichotomically twice. The fusiform neurons are the least numerous in MGB. Most MGB neurons have on the secondary tertiary dendrites and on their ramifications have delicate varicose or bead-like appendages and spine-like protrusions. In all types of neurons an axon arises either from the soma or from the initial portion of the dendritic trunk.