Tenkova T, Chaldakov G N
Department of Anatomy and Histology, Varna Institute of Medicine, Bulgaria.
Cell Tissue Res. 1990 Jul;261(1):205-10. doi: 10.1007/BF00329453.
Transmission electron microscopy was used to examine internalized gap junctions (IGJ) in rabbit and rat ciliary epithelial cells. A prominent feature of all the specimens studied was the presence of different images of IGJ membrane that entrapped a portion of an adjoining cell. We documented and analyzed more than 500 gap junction (GJ) vacuoles and invaginations, the latter comprising less than 20% of all the structures examined. With ten exceptions found in non-pigmented cells, all the IGJ were unidirectionally internalized within the cytoplasm of pigmented epithelial cells. Morphological signs of autophagic degradation of GJ vacuoles were observed. An essential finding was that once a GJ membrane started to invaginate, a "lucidation" of a part of the protruding cytoplasm occurred; no planar GJ membranes exhibited such an alteration. The present finding suggest that IGJ derived from the epithelium of ciliary processes arise through an invagination-endocytosis mechanism and are degraded autophagically. This phenomenon may be relevant to aqueous humor production.
利用透射电子显微镜检查兔和大鼠睫状上皮细胞中的内化间隙连接（IGJ）。所有研究标本的一个显著特征是存在IGJ膜的不同图像，这些图像包裹了相邻细胞的一部分。我们记录并分析了500多个间隙连接（GJ）液泡和内陷，后者占所有检查结构的不到20%。在非色素细胞中发现了十处例外情况，所有IGJ均在色素上皮细胞的细胞质内单向内化。观察到GJ液泡自噬降解的形态学迹象。一个重要发现是，一旦GJ膜开始内陷，突出细胞质的一部分就会出现“透明化”；没有平面GJ膜表现出这种改变。目前的发现表明，源自睫状突上皮的IGJ是通过内陷-内吞机制产生的，并通过自噬降解。这种现象可能与房水生成有关。
