高原鼢鼠和高原鼠兔肺细叶的结构特征

Characteristics of pulmonary acinus structure in the plateau zokor Myospalax baileyi and plateau pika Ochotona curzniae

高原鼢鼠和高原鼠兔是青藏高原土著动物,对低氧具有很好的适应性。为了探讨在低氧环境中两者肺细叶结构的适应特征,应用体视学方法测量了肺细叶相关指标。结果发现:高原鼢鼠和高原鼠兔肺单位面积肺泡数显著高于SD大鼠,单个肺泡面积和弹性纤维/肺实质比显著低于SD大鼠;高原鼢鼠肺泡隔厚度最厚,高原鼠兔最薄,且三种动物具显著差异;高原鼢鼠和高原鼠兔气-血屏障的算术平均厚度(Ta)和调和平均厚度(Th)均显著低于SD大鼠;在三个级别的微血管中,高原鼠兔中膜肌层厚度显著低于高原鼢鼠,两种高原动物均显著低于SD大鼠;高原鼢鼠和高原鼠兔的微血管密度(MVD)显著高于SD大鼠。以上结果表明,高原鼢鼠和高原鼠兔肺细叶结构特征表现出一定趋同,这些特征有利于在低氧条件下提高肺气体扩散容量;但是,肺泡隔厚度和微血管中膜肌层厚度/血管外径比又表现出明显的差异,可能是不同生境造成的。

Abstract The Plateau zokor Myospalax baileyi and plateau pika Ochotona curzniae are species endemic to the Qinghai-Tibet Plateau. To study the adaptive characteristics of pulmonary acinus structure in the two species, we measured relative indices by using stereological methods, using the SD rat as a control model. Results revealed differences in lung weight vs body weight （LVB） among the three species. The LVB value was the highest in plateau zokors, and lowest in SD rats. There was no significant difference in density of pulmonary alveoli （DPA） between plateau zokors and plateau pikas, but the DPAs in the two species were higher than that in the SD rat. The area of pulmonary alveoli （APA） and elastic fibers vs lung parenchyma （EVP） of plateau zokors and plateau pikas were significantly lower than those of SD rats. There were obvious differences in the thickness of the interalveolar septum （TIS） of the three animals. Air-blood barrier arithmetic mean thickness （ Ta ） and harmonic mean thickness （ Th ） were both less than those in SD rats. The muscle thickness vs the outer diameter of microvessels （MVM） and microvessel density （MVD） of plateau zokors and plateau pikas were significantly lower than those in SD rats. The MVM also differed markedly between the two high altitude animals. In conclusion, the structure of the pulmonary acinus in these two high altitude mammals shows obvious similarities indicative of convergent evolution. This reflects adaptation to hypexic environments, for lungs that have strong capacities for oxygen uptake .