藏羊脑动脉系统结构特征与高原适应性研究

摘要

The Tibetan sheep has showed excellent adaptability in extreme cold and hypoxia conditions,and it has been regarded as one of the fittest highland domestic animals.Comparative study on the morphological features of the cerebral arterial system in the Tibetan sheep and Tan sheep will reveal Tibetan sheep's anatomical mechanism high-altitade adaption to some extent.In the study,brain samples from the Tibetan sheep and Tan sheep were collected respectively in Qinghai province and Ningxia Autonomous Region,and vascular corrosion casts of the cerebral arterial system of these sheep were made,then their anatomical structural features were observed and analyzed by comparative anatomic methods.The results found that diameters of the posterior communicating artery and maxillary artery in Tibetan sheep were greater than those of Tan sheep,and average diameters of other arteries in Tibetan sheep were also wide.In addition,in contrast to Tan sheep,there were longer epidural retia mirabile,more developed intracranial cerebral arterial branches,more arterial spread and more abundant small branches in the Tibetan sheep.It was deduced that the cerebral arterial system of Tibetan sheep was more developed than that of Tan sheep.Tibetan sheep appears to allow more efficient blood supply to the brain tissue via the cerebral arterial system.So it was hypothesized that these might be morphological mechanisms of the Tibetan sheep to adapt the plateau environment.%藏羊对严酷的高原低氧环境适应性很强,是高寒牧区最适宜发展的畜种之一,开展藏羊与低海拔绵羊脑血管形态的比较研究,可为探讨藏羊的高原适应性机理奠定基础.研究以高原藏羊—欧拉型藏羊和生活在低海拔地区的滩羊脑为试验材料,采用管道铸型腐蚀技术,运用比较解剖学方法对二者脑动脉系统的结构特性开展研究.比较发现,藏羊和滩羊脑动脉系统的大体解剖结构相同,但藏羊的大脑后交通动脉、上颌动脉的管径显著比滩羊粗,其它脑动脉管径平均值也略大；藏羊脑硬膜外异网显著长于滩羊；藏羊主要脑动脉中的侧支更发达,伸展较长,细小分支更丰富.藏羊有相对发达的脑动脉系统,利于向脑组织有效供血,可能是藏羊适应高原环境的结构特征之—.