Bastacky J, Lee C Y, Goerke J, Koushafar H, Yager D, Kenaga L, Speed T P, Chen Y, Clements J A
Life Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley 94720 USA.
J Appl Physiol (1985). 1995 Nov;79(5):1615-28. doi: 10.1152/jappl.1995.79.5.1615.
The low-temperature electron microscope, which preserves aqueous structures as solid water at liquid nitrogen temperature, was used to image the alveolar lining layer, including surfactant and its aqueous subphase, of air-filled lungs frozen in anesthetized rats at 15-cmH2O transpulmonary pressure. Lining layer thickness was measured on cross fractures of walls of the outermost subpleural alveoli that could be solidified with metal mirror cryofixation at rates sufficient to limit ice crystal growth to 10 nm and prevent appreciable water movement. The thickness of the liquid layer averaged 0.14 micron over relatively flat portions of the alveolar walls, 0.89 micron at the alveolar wall junctions, and 0.09 micron over the protruding features (9 rats, 20 walls, 16 junctions, and 146 areas), for an area-weighted average thickness of 0.2 micron. The alveolar lining layer appears continuous, submerging epithelial cell microvilli and intercellular junctional ridges; varies from a few nanometers to several micrometers in thickness, and serves to smooth the alveolar air-liquid interface in lungs inflated to zone 1 or 2 conditions.
低温电子显微镜可在液氮温度下将含水结构保存为固态水，利用该显微镜对处于15厘米水柱跨肺压下麻醉大鼠中充满空气的肺脏的肺泡内衬层进行成像，包括表面活性剂及其水相下层。在最外层胸膜下肺泡壁的交叉断面上测量内衬层厚度，这些断面可通过金属镜冷冻固定以足够的速率凝固，从而将冰晶生长限制在10纳米并防止明显的水分移动。在肺泡壁相对平坦的部分，液层厚度平均为0.14微米，在肺泡壁交界处为0.89微米，在突出特征上为0.09微米（9只大鼠，20个壁，16个交界处和146个区域），面积加权平均厚度为0.2微米。肺泡内衬层似乎是连续的，淹没了上皮细胞微绒毛和细胞间连接嵴；厚度从几纳米到几微米不等，在膨胀至1区或2区状态的肺中起到使肺泡气液界面平滑的作用。
