An ultrastructural study of the effects of right cervical sympathectomy on the sinuatrial and atrioventricular nodes in the heart of the monkey (Macaca fascicularis).

This study describes the ultrastructural changes in the sinuatrial and atrioventricular nodes of the heart of the monkey (Macaca fascicularis) after right cervical sympathectomy. Obvious changes in the nodal cells were seen one day after operation. Numerous glycogen particles grouped together to form electron-dense patches containing vacuoles in the cytoplasm. At three days after operation, intracellular organelles exhibited fragmentation and dissolution. By five and seven days after operation, the affected cells were vacuolated and some were swollen and appeared to have degenerated. Simultaneously, there was massive infiltration of macrophages were present nodal tissues. Axon profiles and terminals showing various degrees of degeneration were present in the vicinity of the nodal cells throughout the period of study. It is concluded that right cervical sympathectomy resulted in a rapid degeneration in some of the cells in the sinuatrial and atrioventricular nodes.