Electron microscopic demonstrations of filamentous molecular sieve plugs in capillary fenestrae

被引:127
作者
Rostgaard, J
Qvortrup, K
机构
[1] Dept. of Medical Anatomy Section B, University of Copenhagen, Panum Institute, DK-2200 Copenhagen N
关键词
D O I
10.1006/mvre.1996.1987
中图分类号
R6 [外科学];
学科分类号
1002 ; 100210 ;
摘要
The permeability of capillaries is usually explained with reference to ''small pores,'' permeable to water and small solutes, and ''large pores,'' permeable to proteins. Fenestrated capillaries are far more permeable to water and small solutes than nonfenestrated capillaries; moreover, the permeability is highest in the capillaries with the most fenestrae. This suggests that the small pores reside in the fenestral diaphragms; however, no such pores have been illustrated using electron microscopy. In an attempt to clarify this controversy, fenestrated capillaries in the small intestine, stomach, and kidney of the rat were reinvestigated by electron microscopy. A new method of vascular perfusion-fixation was employed, which included the use of glutaraldehyde dissolved in an oxygen-carrying blood substitute (fluorocarbon) and delivered by a peristaltic pump controlled by pressure feedback. The investigation disclosed a prominent endocapillary surface coat, about 50-100 nm thick, and the existence of bush-like filamentous sieve plugs in the fenestrae. Each filamentous plug was composed of 20-40 filaments, each filament measuring 300-400 nm in length and 5-10 nm in thickness. The filamentous plugs have tentatively been named fascinae fenestrae, because they resemble fascines and may also function as such. (C) 1997 Academic Press.
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页码:1 / 13
页数:13
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