牦牛肺脏高原适应性的结构研究

Structural Study on Plateau Adaptability of Yak Lung

【目的】系统观测牦牛肺脏的微细结构,分析其结构特异性与高原低氧环境的适应性。【方法】组织化学反应、特殊染色方法和透射电镜技术及立体定量方法。【结果】牦牛肺小叶结构明显,肺泡I型上皮菲薄,构成肺泡壁的绝大部分。与其它动物不同,牦牛I型肺泡上皮见有间断处,为非连续型上皮。气-血屏障的算术平均厚度和调和平均厚度分别为(0.53±0.10)μm和(0.44±0.07)μm,明显比体格较小的其它家畜还要薄,这有利于气体交换时增加氧的弥散量。肺脏微动脉中膜的肌层厚度与血管外径的百分比为(5.00±0.93)%,与高原驼马的比值近似,而比奶牛和公牛的要小,说明牦牛肺动脉高压的发病率比其它牛类低。肺胸膜、小叶间隔、肺泡隔、各级支气管管壁和血管壁内都有丰富的弹性纤维分布,并相互联系,构成一个完整的弹性系统,维持肺脏良好地扩张和回缩状态。杯状细胞不仅大量分布于各级支气管,细支气管粘膜上皮中也出现杯状细胞,其分泌的粘液有助于牦牛在干旱环境下保护呼吸道的通气量。【结论】牦牛肺脏的结构具有特异性,这是牦牛世代生活于高原低氧环境下所获得的适应性变化。

[ Objective ] The study investigated the fine structure of the yak lung and how it adapts to the plateau. [ Method ] Sections of the lung were examined by histochemistry reaction, some using special staining methods and trans electro-microscopy. The relationship between the morphological features and the adaptability to lower-oxygen was analyzed by stereoscopy. [Result] The lobuli pulmonum occurred obviously. Most of the alveoli wall composed by type Ⅰ alveolar cells and clearly had gaps on it. The arithmetic and conciliate averages of the air-blood barrier thickness were （0.53±0.10）μm and （0.44±0.07）μm respectively, which were notably smaller than that of other smaller livestock. They can facilitate the dispersion of oxygen through the barrier. The rate of muscle-layer thickness to outer diameter of the blood vessel was （5.00±.93）%, similar to the camel horse but smaller than the cow and bull, which can reduce pulmonary artery high pressure. There were many elastic fibres in pulmonary pleura, interlobular connective tissue, alveolar septa, walls of different bronchus and blood vessels, which formed a complete elastic system in favor of the lung dilating and shrinking. Goblet cells that distributed not only in different bronchi but also in bronchioles, were good for dry air passing through the tract. [Conclusion] Several structural features were obtained by yaks as a result of their living in lower-oxygen on Qingzang Plateau from generation to generation.