THE MORPHOMETRY OF THE INTRAMEMBRANOUS PARTICLES OF THE DOG SINUS NODE CELLS——FREEZE REPLICA METHOD STUDY / 解剖学报

The morphometry of the intramembranous particles (IMP) of the dog sinus node cells was studied with freeze-cleaved specimens under H-500 electron microscope. The photographs of IMP of the P cells and transitional cells were analysed with imaging analytical system (IBAS Ⅰ+Ⅱ type). The results are as follows. The mean area of IMP: on PF and EF faces of P cells are 25.800nm~2 and 17.816nm~2. The mean values of IMP on PF and EF faces of the transitional cells are 46.041nm~2 and 88.633nm~2. The averages of the perimeter of IMP on the PF and EF faces of P cells are 20.735 nm and 18.078 nm, respectively. And those of the transitional cells are 28.780 nm and 43.901 nm. The diameters of circles of IMP of PF and EF faces of P cells are 5.220 nm and 4.402 nm. Those of PF and EF faces of the transitional cells are 7.010 nm and 10.476 nm. The mean values of form factor of IMP on PF and EF faces of P cells are 0.653 and 0.643, and those of transitional cells are 0.627 and 0.573. The mumbers of IMP are 1325/?m~2 and 345/?m~2 on PF and EF faces of P cells, and the mumbers of IMP of the transitional cells are 3225/?m~2 on PF face and 590/?m~2 on EF face.

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

The fine structure of the biomembrane of the sinus node cells in the dog wasstudied 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 ofEF faces,In general,the shape of the IMP of the plasma membrane(PF and EFfaces)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 craterson EF faces.No regular array of the vesicles had been observed on both faces,TheIMP of the mitochondrial cristae were more dense than those of the depression.TheIMP of PF face of the nuclear membrane were observed.Their size and shapepresent a uniform appearance.There were many nuclear pores in the surface of thenuclear membrance.In the cytoplasm,longitudinal and transverse sections of the myofibrils werefound.On the transverse section,the myofilaments of A and I band werepresent.The intercalated disk was observed.The gap junctions present between thesinus node cells were proved by Masson-Pevet et al in the rabbits but were notfound in our specimens.