An ultrastructural study of the neuronal changes in the cardiac ganglia of the monkey (Macaca fascicularis) following unilateral vagotomy.

This study describes at the ultrastructural level the neuronal changes in the intracardiac ganglia of the monkey (Macaca fascicularis) following unilateral vagotomy. One day after unilateral vagotomy, some intracardiac neurons showed an overall increase in electron density, with the dendrites darkening first. At three days after operation the dendrites appeared jet black and their intracytoplasmic organelles were hardly distinguishable except for some pale mitochondria. The perikarya of the affected neurons showed a slight increase in electron density. By five and seven days after operation, satellite cells and macrophages with engulfed dendritic processes and degenerated axons were commonly observed. The majority of the intracardiac neurons appeared normal, except for the presence of numerous macrophage (containing several phagosomes) in their vicinities. It is suggested that transneuronal degeneration occurred very rapidly in the heart of the primate, Macaca fascicularis, and that most of the affected neurons appeared to have 'recovered' one week after unilateral vagotomy.