Endothelial fenestral diaphragms: a quick-freeze, deep-etch study
The route by which water, solutes, and macromolecules traverse the endothelial cell has long been a subject of study for both physiologists and cell biologists. Recent physiologic studies describe a slit-shaped pore (5.1-5.7-nm wide) as the communicating channel, although no channel of such dimensio...
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| Format: | Online |
| Language: | English |
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The Rockefeller University Press
1985
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| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2113429/ |
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pubmed-2113429 |
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pubmed-21134292008-05-01 Endothelial fenestral diaphragms: a quick-freeze, deep-etch study Bearer, EL Orci, L Articles The route by which water, solutes, and macromolecules traverse the endothelial cell has long been a subject of study for both physiologists and cell biologists. Recent physiologic studies describe a slit-shaped pore (5.1-5.7-nm wide) as the communicating channel, although no channel of such dimensions has been visible in electron microscopic preparations. That this channel should be found within the fenestral diaphragm has long been suggested. In this report, by the aid of a new technique in tissue processing, we are able to demonstrate a possible morphologic correlate within the fenestral diaphragm of fenestrated capillaries. Quick-freezing and deep-etching of whole tissue blocks allows the sublimation of water from the endothelial pores, thus leaving the channels through the diaphragms empty and readily replicated with a platinum-carbon shadow. The structure of the diaphragm was revealed thus to be composed of radial fibrils of 7 nm in diameter, interweaving in a central mesh, and creating by their geometric distribution, wedge-shaped channels around the periphery of the pore. The average channel had a maximum arc length of 5.46 nm. Fenestrated endothelia from various tissues, including endocrine and exocrine pancreas, adrenal cortex, and kidney peritubular capillaries, displayed the same diaphragmatic structure, whereas continuous capillaries in muscle had no such diaphragm. Photographic augmentation of electron micrographs of etched replicas displayed marked enhancement at n = 8, confirming an octagonal symmetry of the fenestral diaphragm. Finally, cationic ferritin, clearly visible as a marker after etching, heavily bound to the flowerlike structure within the fenestral pore. We conclude that the fenestral diaphragm contains the structure responsible for fenestrated capillary permeability and that the communicating channel has the shape of a wedge. The Rockefeller University Press 1985-02-01 /pmc/articles/PMC2113429/ /pubmed/3968170 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
| repository_type |
Open Access Journal |
| institution_category |
Foreign Institution |
| institution |
US National Center for Biotechnology Information |
| building |
NCBI PubMed |
| collection |
Online Access |
| language |
English |
| format |
Online |
| author |
Bearer, EL Orci, L |
| spellingShingle |
Bearer, EL Orci, L Endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| author_facet |
Bearer, EL Orci, L |
| author_sort |
Bearer, EL |
| title |
Endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| title_short |
Endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| title_full |
Endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| title_fullStr |
Endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| title_full_unstemmed |
Endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| title_sort |
endothelial fenestral diaphragms: a quick-freeze, deep-etch study |
| description |
The route by which water, solutes, and macromolecules traverse the endothelial cell has long been a subject of study for both physiologists and cell biologists. Recent physiologic studies describe a slit-shaped pore (5.1-5.7-nm wide) as the communicating channel, although no channel of such dimensions has been visible in electron microscopic preparations. That this channel should be found within the fenestral diaphragm has long been suggested. In this report, by the aid of a new technique in tissue processing, we are able to demonstrate a possible morphologic correlate within the fenestral diaphragm of fenestrated capillaries. Quick-freezing and deep-etching of whole tissue blocks allows the sublimation of water from the endothelial pores, thus leaving the channels through the diaphragms empty and readily replicated with a platinum-carbon shadow. The structure of the diaphragm was revealed thus to be composed of radial fibrils of 7 nm in diameter, interweaving in a central mesh, and creating by their geometric distribution, wedge-shaped channels around the periphery of the pore. The average channel had a maximum arc length of 5.46 nm. Fenestrated endothelia from various tissues, including endocrine and exocrine pancreas, adrenal cortex, and kidney peritubular capillaries, displayed the same diaphragmatic structure, whereas continuous capillaries in muscle had no such diaphragm. Photographic augmentation of electron micrographs of etched replicas displayed marked enhancement at n = 8, confirming an octagonal symmetry of the fenestral diaphragm. Finally, cationic ferritin, clearly visible as a marker after etching, heavily bound to the flowerlike structure within the fenestral pore. We conclude that the fenestral diaphragm contains the structure responsible for fenestrated capillary permeability and that the communicating channel has the shape of a wedge. |
| publisher |
The Rockefeller University Press |
| publishDate |
1985 |
| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2113429/ |
| _version_ |
1611412632002101248 |