McLaughlin B J, Caldwell R B, Sasaki Y, Wood T O
Curr Eye Res. 1985 Sep;4(9):951-61. doi: 10.3109/02713689509000002.
The intramembrane structure of epithelial apical, lateral and basal membranes was compared with that of the endothelium in normal rabbit corneas. The cytoplasmic membrane leaflet (P-face) of apical epithelial membrane displays randomly scattered intramembrane particles over the apical microvilli. Apical endothelial P-face membranes, by comparison, are covered by densely-packed particles. The lateral membranes of superficial epithelial cells display delicate tight junctions, punctate particle aggregates characteristic of desmosomes, and small gap junctions. Background intramembrane particles are randomly distributed and not densely packed. Large gap junctions and fewer desmosomes are present on deeper epithelial cells, including basal cells. By comparison, the endothelial lateral membranes display densely-packed, background particles and numerous triangular-shaped, gap junctional particle aggregates bordered by strands of particles resembling tight junctions. At the apical border, long anastomosing tight junctional strands are present. The basal E-face membranes of both cell layers adjacent to the basement membrane are similar in that they have sparse particles and vesicle fusion sites. Small particle aggregates are present on basal epithelial membranes at sites of hemidesmosomes. Quantitation of particle size and density on P-face apical and lateral membranes of each cell layer reveals that particle density on endothelial membranes is more than twice that on epithelial membranes. Particle sizes are similar on both cell layers and mean diameter ranges from 8.7 to 9.2 nm. The differences in intramembrane particle density and junctional aggregates on epithelial and endothelial membranes reflect membrane constituents associated with functional differences of these two cell layers.
在正常兔角膜中，对上皮细胞顶端、侧面和基底膜的膜内结构与内皮细胞的膜内结构进行了比较。顶端上皮膜的细胞质膜小叶（P面）在顶端微绒毛上显示出随机散布的膜内颗粒。相比之下，顶端内皮细胞的P面膜被密集排列的颗粒覆盖。浅层上皮细胞的侧面膜显示出精细的紧密连接、典型的桥粒点状颗粒聚集体以及小的缝隙连接。背景膜内颗粒随机分布，并非密集排列。在包括基底细胞在内的较深层上皮细胞上存在大的缝隙连接和较少的桥粒。相比之下，内皮细胞的侧面膜显示出密集排列的背景颗粒以及许多三角形的缝隙连接颗粒聚集体，其边界由类似紧密连接的颗粒链构成。在顶端边界处，存在长的吻合紧密连接链。与基底膜相邻的两层细胞的基底E面膜相似，都有稀疏的颗粒和囊泡融合位点。在基底上皮膜上半桥粒部位存在小颗粒聚集体。对各细胞层顶端和侧面膜P面上颗粒大小和密度的定量分析表明，内皮细胞膜上的颗粒密度是上皮细胞膜上颗粒密度的两倍多。两层细胞上的颗粒大小相似，平均直径在8.7至9.2纳米之间。上皮细胞和内皮细胞膜内膜内颗粒密度和连接聚集体的差异反映了与这两层细胞功能差异相关的膜成分。
