A scanning electron microscopic study of the atrioventricular bundle of the ferret.

Scanning electron microscopy was used to examine the three-dimensional morphology of atrioventricular (AV) bundle cells in the ferret heart. These cells are organized into fascicles with extensive intercellular contact between cells within a fascicle and less contact between cells of different fascicles. The cell surface shows conspicuous ridges and depressions, as well as smooth regions. The distribution of myofibrils within an AV bundle cell is not uniform. Mitochondria of these cells are oval to round, and randomly distributed throughout the sarcoplasm. Junctions between cells within a fascicle are often complex with processes at the end of one cell interdigitating with those of another. In the proximal AV bundle, located above the anulus fibrosus, a small number of large cells are interspersed among the AV bundle cells.