the anatomy of the atrioventricular bundle in the heart of domestic cats (felis catus)

the detailed anatomy and histology of the atrioventricular bundle (avb) was studied in 10 adult cats (5 males and 5 females). the trunk of the atrioventricular bundle was a direct continuation of the atrioventricular node (avn) with no sharp line of demarcation between node and the bundle. the avb of the male cats measured 6.24 mm in length, 0.27 mm in width and 0.65 mm in thickness, while in the female cats it was 4.75 mm in length , 0.22 mm in width and 0.55 mm in thickness. the mean width of the right bundle branch (rbb) in male cats was 0.24 mm, while in the female cats it was 0.22 mm. the mean width of the left bundle branch (lbb) in the male cats was 0.46 mm, while in the female cats it was 0.41 mm. also the length of lbb in the male cats was 6.60 mm, while in the female cats it was 5.63 mm. histologically, the fibrous of the avb appeared to be organized into fascicles separated by fine fibrous septa. the cells of the avb were ovoid in shape with light cytoplasm and a central nucleus. the size of these cells were shorter and broader than working myocardial cells and stained paler than them. myofibrils were located at the periphery of the cells and a large perinuclear clear zone that contained a large amount of glycogen were present. these cells showed faint cross striations and there was no intercalated disc at intercellular connections.