Ultrastructure and Cytoarchitecture of Bachmann's Bundle in the Mammalian Heart

Abstract

Recently, the Bachmann's bundle (BB) has been examined in connection with atrial fibrillation. However, the morphological properties of the BB remain to be clarified. In this study, the BB in hearts of monkeys and sheep was investigated by immunohistochemistry, scanning (SEM) and transmission (TEM) electron microscopy. Immuno-histochemically, BB myocytes showed a strong positive reaction for desmin antibody and that connexin (Cx) 40 and Cx43 were distributed at the intercalated disks. BB myocytes were characterized by a dense network of intermediate filaments which enveloped nucleus, myofibrils and mitochondria, respectively. The intercalated disks showed an irregular stair-like profile. Microprojections on the steps were smaller in number and larger in size than those in auricular myocytes. In conclusion, BB myocytes were different ultrastructurally from auricular myocytes, showing morphological properties of the conduction system.

Keywords

• Bachmann's bundle
• intercalated disk
• intermediate filament
• Cx40
• morphology