犬窦房结细胞生物膜的亚显微结构——冷冻复型法

THE ULTRASTRUCTURE OF THE B(?)OMEMBRANE OF THE DOG SINUS NODE CELL——BY FREEZE REPLICAS METHOD

应用6只成体犬心脏窦房结,经冷冻、断裂和蚀划,并喷铂和碳,获得复型膜,于 H-500型透射电镜下观察。在窦房结细胞质膜的 PF 面和 EF 面可见大小不等的球形或半球形膜内微粒。微粒排列的疏密程度不同,且在质膜的不同部位,微粒的大小和分布也不尽一致。在质膜的 PF 面和 EF 面尚可见吞饮小泡,配布无一定规律。在胞质的复型面上可见肌原纤维的纵断和横断面。横断面可显示 A 带的粗丝和细丝相间排列,以及Ⅰ带的细丝蚀刻。被劈裂的线粒体膜和线粒体嵴均可见比较粗大的膜内微粒。核膜的 PF 面有膜内微粒均匀配布,在核膜的表面可见核孔。相邻细胞之间可见质膜并列及端与端之间的闰盘。窦房结的间质尚可见胶原纤维、成纤维细胞和毛细血管等。

The fine structure of the biomembrane of the sinus node cells in the dog was studied with the replicas of freezecleaved specimens.The intramembranous particles. (IMP)in the PF and EF faces of the plasma mcmbrane of the sinus node cells, were present.The density of the IMP on the PF faces was more dense than those of EF faces,In general,the shape of the IMP of the plasma membrane(PF and EF faces)exhibited spherical or spheroidal.The IMP of PF faces may be divided into, three groups,i.e.the larger,medium and small size.Numerous endocytotic vesicles. found on the PF faces appeared as circular depressions and as small walled craters on EF faces.No regular array of the vesicles had been observed on both faces,The IMP of the mitochondrial cristae were more dense than those of the depression.The IMP of PF face of the nuclear membrane were observed.Their size and shape present a uniform appearance.There were many nuclear pores in the surface of the nuclear membrance. In the cytoplasm,longitudinal and transverse sections of the myofibrils were found.On the transverse section,the myofilaments of A and I band were present.The intercalated disk was observed.The gap junctions present between the sinus node cells were proved by Masson-Pevet et al in the rabbits but were not found in our specimens.