Gardiner T A, Archer D B
Br J Ophthalmol. 1986 May;70(5):361-72. doi: 10.1136/bjo.70.5.361.
The endocytosis of horseradish peroxidase (HRP) by the vascular cells of retinal and choroidal blood vessels was compared in immersion and perfusion fixed eyes from individual rats. The mechanisms of endocytosis of HRP appeared identical in both retinal and choroidal vessels. The bulk of internalised tracer occurred in macropinosomes 300-400 nm in diameter. Tracer was localised to a 20-30 nm layer on the internal aspect of the limiting membrane. This layer was coincident with the glycocalyx of the luminal plasma membrane as revealed by ruthenium redosmium tetroxide staining. Horseradish peroxidase was also internalised by a small scattered population of vesicles (100-130 nm in diameter). The size of these vesicles suggested that they may have arisen from clathrin coated regions of the plasma membrane. It is suggested that the endocytosis of HRP in retinal and choroidal vascular endothelium occurs as a function of plasma membrane recycling. Horseradish peroxidase may also be internalised as a 'contaminant' of the glycocalyx in coated pits involved in receptor mediated endocytosis. The smooth 80 nm plasmalemmal caveolae of the retinal and choroidal vascular endothelial cells did not appear to participate either in absorptive endocytosis or vesicular transport.
在对来自个体大鼠的浸没固定和灌注固定眼睛中，比较了视网膜和脉络膜血管的血管细胞对辣根过氧化物酶（HRP）的内吞作用。HRP在视网膜和脉络膜血管中的内吞机制似乎相同。内化示踪剂的大部分存在于直径为300 - 400 nm的大胞饮体中。示踪剂定位于限制膜内侧20 - 30 nm的层中。如钌红-四氧化锇染色所示，该层与腔面膜的糖萼重合。辣根过氧化物酶也被一小群分散的小泡（直径100 - 130 nm）内化。这些小泡的大小表明它们可能起源于质膜的网格蛋白包被区域。提示视网膜和脉络膜血管内皮中HRP的内吞作用是质膜循环的一种功能。辣根过氧化物酶也可能作为参与受体介导内吞作用的包被小窝中糖萼的“污染物”而被内化。视网膜和脉络膜血管内皮细胞光滑的80 nm质膜小窝似乎既不参与吸收性内吞作用也不参与小泡运输。
