Geiser M, Im Hof V, Siegenthaler W, Grunder R, Gehr P
Institute of Anatomy, Inselspital, University of Bern, Switzerland.
Microsc Res Tech. 1997 Mar 1;36(5):428-37. doi: 10.1002/(SICI)1097-0029(19970301)36:5<428::AID-JEMT13>3.0.CO;2-U.
For particle retention and clearance, the structure and surface properties of the airway lining layer are important. Due to difficulties of its preservation, structural analysis has been hampered, and, hence, the existence of two distinct and continuous phases and how much osmiophilic material is available are unclear. It was the objective of this study to investigate the ultrastructure of the aqueous lining layer in the intrathoracic conducting airways of hamsters. By means of transmission electron microscopy, we investigated the ultrastructure of the airway lining layer in hamsters whose lungs have been fixed by the application of fixative dissolved in nonpolar fluorocarbon, either by instillation via the trachea or injection into the gas exchange parenchyma, together with intravascular perfusion of aqueous fixatives. The results were compared to lungs fixed by intravascular perfusion only. In twelve hamsters, the airway lining layer was found to consist of an aqueous phase and was coated by an osmiophilic film that follows fairly closely the upper-extending contours of cilia protruding from epithelial cells. Substantially less osmiophilic material was preserved in extrapulmonary airways and when nonaqueous fixative was injected. We found that the aqueous lining layer of the intrathoracic airways in hamsters essentially surrounds and covers the cilia, the microvilli, and any other structures like macrophages or deposited particles contained in it and is coated by an osmiophilic film of variable thickness. In healthy animals, a gel phase is expected to be very thin, not clearly separated from the periciliary fluid, and located just beneath the osmiophilic film.
对于颗粒的滞留和清除，气道内衬层的结构和表面特性很重要。由于其保存困难，结构分析受到阻碍，因此，两个不同且连续的相的存在以及有多少嗜锇物质可用尚不清楚。本研究的目的是调查仓鼠胸内传导气道中水性内衬层的超微结构。通过透射电子显微镜，我们研究了仓鼠气道内衬层的超微结构，这些仓鼠的肺通过将溶解在非极性氟碳中的固定剂经气管滴注或注入气体交换实质进行固定，并同时进行血管内灌注水性固定剂。将结果与仅通过血管内灌注固定的肺进行比较。在12只仓鼠中，发现气道内衬层由水相组成，并被一层嗜锇膜覆盖，该膜相当紧密地跟随从上皮细胞突出的纤毛的向上延伸轮廓。在肺外气道以及注射非水性固定剂时，保存的嗜锇物质明显较少。我们发现，仓鼠胸内气道的水性内衬层基本上包围并覆盖纤毛、微绒毛以及其中包含的任何其他结构，如巨噬细胞或沉积颗粒，并被一层厚度可变的嗜锇膜覆盖。在健康动物中，凝胶相预计非常薄，与纤毛周围液体没有明显分离，并且位于嗜锇膜下方。
