Abstract
The dorsal motor nucleus of the rat vagus was studied using the Nissl and Klüver-Barrera methods. This nucleus is elongated rostrocaudally, is about 3-4 mm in length and contains about 5,000 cells. It appears fusiform in shape and is subdivided into oral, middle and caudal regions according to cell distribution. These regions constitute one-fifth, two-fifths and two-fifths of the entire length of the nucleus, and the number of cells in each region is about 10%,70%, and 20% of the cell total, respectively. The cells of the nucleus are classified into two distinct types, being either small or medium-sized. Small cells are round or oval in shape, measuring less than 20μm along the long axis and 15μm along the short axis. This type of cell is distributed throughout all regions of the nucleus and represents approximately 60% of all cells. Medium-sized cells are pyramidal or multipolar in shape and measure 20-30μm along the long axis and 15-20μm along the short axis. This type of cell is distributed throughout the central three-fifths of the nucleus and represents approximately 40% of all cells.
