高原型藏羊和小尾寒羊睾丸小叶及附睾微动脉的解剖学特征

Anatomical Characteristics of Testicular Lobule and Epididymal Arterioles in Tibetan Sheep and Small-Tailed Han Sheep

分别从青海和甘肃采集高原型藏羊(Ovis aries)和小尾寒羊睾丸各20枚,用血管铸型技术和扫描电镜方法,研究两品种绵羊睾丸小叶及附睾微动脉的超微形态特征。结果显示,两品种绵羊的睾丸小叶及附睾微动脉走形呈一定程度的弯曲,其中睾丸小叶内离心动脉、离心小动脉及向心小动脉均呈"树枝"状分布。研究发现,与低海拔地区的小尾寒羊相比,高原型藏羊睾丸的绳结状动脉具有更密集的螺旋状排布,小动脉分支也较多,并且向心动脉、绳结状动脉、离心动脉、附睾头微动脉的管径也较粗。此外,高原型藏羊睾丸小叶和附睾头微动脉表面的"梭形"压痕较浅,而小尾寒羊的则较深;高原型藏羊睾丸小叶毛细血管前微动脉的表面缢痕较多且密集,而小尾寒羊的则相对少而稀疏。研究认为,高原型藏羊睾丸小叶及附睾微动脉的超微形态特征,有利于血管的收缩、睾丸供血及高原环境下精子的成熟,是睾丸对高原环境的适应性特征。

Tibetan sheep live in high altitude areas and possess good adaptability to high-altitude hypoxia. As the critical organs of spermatogenesis and sperm transportation, testicles are extremely sensitive to environment. The testicular and epididymal arterioles are regulated by the autonomic nervous system and control the blood flow in the entire microcirculation duct. Here, twenty testes of Tibetan sheep and Small-Tailed Han sheep were collected from their living areas including Qinghai and Gansu, respectively. The morphological characteristics of arterioles in testicular lobule and epididymides were investigated by using the blood perfusion technology and scanning electron microscopic method. The results demonstrated that arterioles of testicular lobule and epididymis exhibited a degree of curvature, and small arteries from the centripetal and centrifugal parts showed "dendritic" distribution (Fig. 1). It was found that spiral of knot-like artery in Tibetan sheep showed tighter and more branches of small arteries than that in Small-Tailed Han sheep. The diameters of centripetal, Knot-like, centrifugal arteries and caput epididymal artery in Tibetan sheep were larger than those of Small-Tailed Han sheep (Table 1). Moreover, there were shallow imprints of the smooth muscles on the surface of testicular lobule and caput epididymis casts, but those in Small-Tailed Han sheep were deeper. Meanwhile there were more and intense precapillary constrictions in testicular lobule than those in Small-Tailed Han sheep (Fig. 2). The study suggested that the arteriole of testicular lobule and epididymis in Tibetan sheep contribute to vasoconstriction and sperm maturation, which became important anatomical characteristics for their adaptation to the plateau environment.