Scheuermann D W, de Maziere A
Acta Morphol Neerl Scand. 1984 Jul;22(2):123-31.
In thin sections and in freeze-fracture replicas small and sparse gap junctions appear to be developed on the longitudinal plasma membrane of Protopterus cardiac cells near a macula or fascia adhaerens. By thin-section electron microscopy, they had septalaminar profiles with a length between 0.042 and 0.260 micron. In freeze-fracture images they appear on the P-fracture face as maculate particle aggregations with complementary pits on the E-fracture face. Particles with a central intercellular channel could be observed. The average center-to-center distance between neighbouring particles or pits is 10.05 +/- 1.87 nm (N = 2429). The diameter of the junctional maculae in replicas lies between 0.037 and 0.229 nm. The particle packing density increases in larger maculate aggregations, while particle-free areas emerge which could be related to the degradation or reformation of gap junctions Atypical configurations of gap junctions observed in the myocardium of lower vertebrates are rarely encountered in this primitive vertebrate.
在薄片和冷冻蚀刻复制品中，在原鳍鱼类心脏细胞靠近斑或黏着小带的纵向质膜上似乎形成了小而稀疏的缝隙连接。通过超薄切片电子显微镜观察，它们具有间隔层状轮廓，长度在0.042至0.260微米之间。在冷冻蚀刻图像中，它们出现在P面断裂面上，呈斑点状颗粒聚集，在E面断裂面上有互补的凹坑。可以观察到带有中央细胞间通道的颗粒。相邻颗粒或凹坑之间的平均中心距为10.05±1.87纳米（N = 2429）。复制品中连接斑的直径在0.037至0.229纳米之间。在较大的斑点状聚集体中颗粒堆积密度增加，同时出现无颗粒区域，这可能与缝隙连接的降解或重塑有关。在这种原始脊椎动物中很少遇到在低等脊椎动物心肌中观察到的缝隙连接的非典型构型。
