Types of neurons in nucleus gracilis and nucleus cuneatus of the European bison.

The study was carried out on the medullae oblongatae of four European bisons. Preparations were made according to the Nissl, Klüver-Barrera and Golgi methods. Nucleus gracilis and nucleus cuneatus of the European bison are formed of 4 types of neurons. Type I--triangular cells. The perikaryon issues 3 dendrites bifurcating once or twice. The dendritic field is ball-shaped. A single thin axon emerges directly from the soma. Tiny granules of the tigroidal substance are very densely distributed and penetrate into the initial segments of dendrites. Type II--multipolar cells. These neurons have 7-9 thick dendrites which bifurcate twice. The dendritic field is ball-shaped. A single axon, 2 microns thick, emerges directly from the perikaryon. The cells contain thick spherical granules of the tigroidal substance. Type III--fusiform cells. From both poles of the perikaryon 2-3 thick dendrites originate which first bifurcate and next give off 2-3 branches. At each pole of the cell there is a separate dendritic field having a stream-like form. The axon arises from the lateral surface of the perikaryon. The tigroidal substance has a form of elongate bands. Type IV--rounded cells. Three thick dendrites are concentrated at one pole of the cell. The dendrites give off collaterals and ramify. The dendritic field has a stream-like form. The axon emerges from the perikaryon, a long distance from the dendrites. Thick granules of the tigroidal substance are evenly distributed in the cell.