Meban C
Cell Tissue Res. 1977 Jul 11;181(2):267-75. doi: 10.1007/BF00219986.
The respiratory epithelium in the lungs of the tortoise (Testudo graeca) has been studied by electron microscopy. The epithelium consists of a mosaic of two different cell types (here called "pneumonocytes"). Type I pneumonocytes are roughly squamous and possess attenuated flanges of cytoplasm which extend over the septal capillaries. Localized cytoplasmic expansions are often present near the periphery of these flanges. Most of the organelles are concentrated in the perinuclear region; the most prominent of these are the mitochondria and osmiophilic inclusions. In contrast, type II pneumonocytes are cuboidal and are richly endowed with organelles including large Golgi complexes, extensive endoplasmic reticulum and numerous inclusion bodies. The morphological evidence suggests that type I pneumonocytes are involved in the secretion of osmiophilic material (presumed to be pulmonary surfactant) and in maintaining the integrity of the air-blood barrier. Type II pneumonocytes appear to be concerned solely with the production of surfactant.
通过电子显微镜对希腊陆龟（Testudo graeca）肺部的呼吸上皮进行了研究。上皮由两种不同细胞类型（此处称为“肺细胞”）组成的镶嵌体构成。I型肺细胞大致呈鳞状，具有延伸至间隔毛细血管上的细胞质薄缘。这些薄缘周边附近常出现局部细胞质扩张。大多数细胞器集中在核周区域；其中最突出的是线粒体和亲锇性内含物。相比之下，II型肺细胞呈立方形，富含包括大型高尔基体复合体、广泛的内质网和众多包涵体在内的细胞器。形态学证据表明，I型肺细胞参与亲锇性物质（推测为肺表面活性物质）的分泌以及维持气血屏障的完整性。II型肺细胞似乎仅与表面活性物质的产生有关。
