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.
)