van den Hoef M H, Dictus W J, Hage W J, Bluemink J G
Eur J Cell Biol. 1984 Mar;33(2):242-7.
The cellular contact sites between the full-grown oocyte of Xenopus laevis and the surface extensions of surrounding follicles cells were analysed by electron microscopy of ultrathin sections, freeze-fracture replicas and critical point-dried specimens. Evidence is given for the presence of clusters of intramembranous particles (IMPs) at the P-face which represent gap junctions in diverse forms. Most common are maculae (phi 0.2-0.5 micron) of densely packed IMPs (phi 12 +/- 2 nm) which represent focal gap junctions generally found at the tips of follicle cell surface extensions. Inside many maculae an IMP-free area occurs which appears as a smooth disk (phi 70-80 nm) at both fracture faces. Occasionally a few IMPs are trapped within the smooth disks. Beside the maculae, networks of arrayed IMPs occur that enclose several smooth disks. These latter gap junctions probably are more frequent in side-to-side contacts between surface extensions of the oocyte and the follicle cells. The possible function of these IMP networks is discussed as being related to similar membrane specializations in excitable cells. In addition, indirect evidence was found that the extensions of the follicle cells transport yolky material.
通过超薄切片、冷冻蚀刻复制品和临界点干燥标本的电子显微镜分析，研究了非洲爪蟾成熟卵母细胞与周围卵泡细胞表面延伸部分之间的细胞接触位点。有证据表明，在P面上存在膜内颗粒（IMPs）簇，它们代表了不同形式的间隙连接。最常见的是斑（直径0.2 - 0.5微米），其中密集排列着IMP（直径12 +/- 2纳米），这些斑代表了通常在卵泡细胞表面延伸末端发现的局灶性间隙连接。在许多斑内部有一个无IMP区域，在两个断裂面上都呈现为一个光滑的圆盘（直径70 - 80纳米）。偶尔有一些IMP被困在光滑圆盘中。除了斑之外，还出现了排列成阵列的IMP网络，这些网络包围着几个光滑圆盘。后一种间隙连接可能在卵母细胞和卵泡细胞表面延伸部分的侧向接触中更常见。讨论了这些IMP网络的可能功能与可兴奋细胞中类似膜特化的关系。此外，还发现了间接证据，表明卵泡细胞的延伸部分运输含卵黄物质。
