人窦房结的神经发育

本文用14例不同发育阶段的胚胎,以及新生儿与成人各2例的窦房结,以Faworsky法银染,光镜观察。8周胚在腔房交界处的前内侧,出现局限性增厚,该区致密,细胞较小,尚未包绕窦房结动脉;至12周时,该区称为窦房结,已见少量纤细的神经纤维。16～22周胚胎的窦房结切面呈椭圆形,窦房结动脉位于中央,已能分出三个区。中央网状区内,神经节与神经纤维丰富,心外膜下神经节较少。神经细胞为多极神经元,胞体大小不一,核质比例为幼稚形细胞状态。24～32周的胚胎心外膜下神经节数量逐渐增多,可以分出深、浅两组;结内神经节则逐渐减少。此阶段结外节已多于结内节。38周胚胎与新生儿的窦房结神经配布,与24～32周胚胎阶段相似,只是更趋于成熟,接近成年人窦房结的神经分布特点。

THE DEVELOPMENT OF INNERVATIONS OF SINOATRIAL NODE IN THE FETUSES

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 follows:1. 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.