正常人类小梁网中的内皮细胞间连接对压力变化有反应。

Interendothelial junctions in normal human Schlemm's canal respond to changes in pressure.

作者信息

Ye W, Gong H, Sit A, Johnson M, Freddo T F

机构信息

Eye Pathology Laboratory, Boston University School of Medicine, Massachusetts 02118, USA.

出版信息

Invest Ophthalmol Vis Sci. 1997 Nov;38(12):2460-8.

PMID:9375563

Abstract

PURPOSE

To determine if changes in the structure and complexity of junctions between endothelial cells lining Schlemm's canal (SC) occur in normal human eyes with changes in perfusion pressure.

METHODS

Twelve normal human eyes were either perfusion-fixed (at 15 or 45 mm Hg) or immersion-fixed (0 mm Hg) in modified Karnovsky's fluid. 'Outflow facility was measured continually during the perfusion fixation. The intercellular junctions of the endothelial cells of SC were ultrastructurally examined in thin sections, including serial sections and freeze-fracture replicas. Morphometric data on the number of junctional strands per total length of tight junction were documented and categorized by the number of strands (one, two, or three or more). The length of endothelial cell overlap was measured on thin sections.

RESULTS

In freeze-fracture replicas, perfusion-fixed eyes demonstrated less complex junctions. At 15 mm Hg, 18.06% of the total junctional length was represented by three or more strands; at 45 mm Hg, this percentage decreased to 8.59%. In immersion-fixed eyes, 24.17% of the total junctional length was represented by three or more strands. These differences were statistically significant (P < 0.0012). In sections, the amount of endothelial cell overlap, and thus the length of paracellular pathway, was reduced in perfusion-fixed versus immersion-fixed eyes (P < 0.02). Extensive serial sectioning demonstrated that giant vacuoles were formed, either by individual endothelial cells or by two or more adjacent endothelial cells.

CONCLUSIONS

When compared with specimens fixed at zero pressure, overlap between endothelial cells of SC is reduced significantly when this cell layer is under conditions of flow similar to those encountered in vivo. The tight junctions between cells of the inner wall of SC become less complex with increasing pressure. Our data suggest that the paracellular pathway into SC in the normal eye is sensitive to modulation within a range of physiologically relevant pressures.

摘要

目的

确定在灌注压改变时，正常人类眼中施莱姆管（SC）内衬内皮细胞之间连接结构和复杂性的变化情况。

方法

12只正常人类眼睛在改良的卡诺夫斯基固定液中进行灌注固定（15或45毫米汞柱）或浸入固定（0毫米汞柱）。在灌注固定过程中持续测量流出设施。对SC内皮细胞的细胞间连接进行超薄切片的超微结构检查，包括连续切片和冷冻断裂复制品。记录紧密连接每总长度的连接链数量的形态计量学数据，并按链的数量（一、二或三条及以上）进行分类。在超薄切片上测量内皮细胞重叠的长度。

结果

在冷冻断裂复制品中，灌注固定的眼睛显示出连接结构较不复杂。在15毫米汞柱时，总连接长度的18.06%由三条及以上链表示；在45毫米汞柱时，该百分比降至8.59%。在浸入固定的眼睛中，总连接长度的24.17%由三条及以上链表示。这些差异具有统计学意义（P < 0.0012）。在切片中，与浸入固定的眼睛相比，灌注固定的眼睛中内皮细胞重叠量以及因此细胞旁通路的长度减少（P < 0.02）。广泛的连续切片显示，巨型液泡由单个内皮细胞或两个或更多相邻内皮细胞形成。