THE DEVELOPMENT OF INNERVATIONS OF SINOATRIAL NODE IN THE FETUSES / 解剖学报

ABSTRACT

The development of innervations of sinoatrial node in 14 fetuses and two new borns was studied by Faworsky's silver impregnation technique and the results were summarized as follows1. The ganglia and rich nerve fibers can be observed within the sinoatrial node in approximately 16-week old fetus. It was found that in 16 to 20-week old fetus there were more nerve ganglia within the node than in the subepicardial region.2. After 24 week, the nerve ganglia of the subepicardial region were divided in to two groups, i. e, the superficial and profund groups. Their number were larger than that of the peripheral ground around the artery in the node. The nerve bun-dles were thinker and richer.3. The nerve ganglionic cells with two or more nuclei were frequently found within sinoatrial node of fetuses and new borns but are rare in adults. The size of the nerve ganglion cells in the early stages of fetuses is various but they become more similar in size with the advancing age of the fetus towards maturity.