INNERVATION OF THE SINOATRIAL NODE OF THE DOG / 解剖学报

ABSTRACT

The innervation of sino-atrial node in 5 dogs demonstrated by Faworsky's silver impregnation technique was studied and the results were summarized as follows: 1.On the basis of observation under microscope,two-third of the area adjacent to the suleus terminalis was found to be occupied by the main part of the sino-atrial node in the dog. 2.The nerve ganglia in the sino-atrial node and its peripheral zone were distingu- ished in two groups. 1)The Subepicardial group,i.e,the nerve ganglia of the peripheral zone around the node:It consists of the superficial and profund groups.Most of the nerve ganglia are present close to the sulcus terminalis and become less in number as approaching the cava- auricular angle.The largest nerve ganglion comprising of 30 cells could be seen with naked eye on the section,and the smaller ones are those with individnd cells. 2)Peripheral group around the artery,i,e the nerve ganglia within the node:They were situated around the sino-atrial artereis adjacent to the sulcus terminalis.Occasionally two ganglia may appear in one visual field.They were scattered among the nodal cells and also among myocardial fibers between the sino-atrial node and the endocardium. The characteristics of the structure of the nerve ganglia in both groups were described. 3)The relation of the nerve bundles and the nerve ganglia was studied in detail. The authors presumed that both the parasympathetic postganglionic fibers and parasympa- thetic preganglionic fibers existed in the sino-atrial node.