中文摘要：

为观察牦牛淋巴结发育过程中组织结构的变化,研究牦牛淋巴结的结构发育特点,选取新生、1岁及成年健康牦牛肠系膜和下颌淋巴结样本,运用组织学方法对其组织结构进行观察与分析。结果,新生牦牛淋巴结内可见初级和次级淋巴小结,1岁及成年牦牛淋巴结中以次级淋巴小结为主。牦牛淋巴结单位面积内生发中心数量及皮质相对面积百分比随年龄增长呈先上升后下降的趋势,1岁时最高,成年次之,新生最低,各组之间差异显著（P〈0.05）;髓质相对面积百分比随年龄增长呈先下降后上升的趋势,新生最高,成年次之,1岁时最低,各组之间差异显著（P〈0.05）。除新生牦牛外,1岁及成年牦牛下颌淋巴结生发中心数量均显著多于肠系膜淋巴结（P〈0.05）;三个年龄组中下颌淋巴结皮质相对面积百分比均显著高于肠系膜淋巴结（P〈0.05）,肠系膜淋巴结髓质相对面积百分比均显著高于下颌淋巴结（P〈0.05）。上述结果表明,牦牛在出生早期其淋巴结内已经形成生发中心,牦牛淋巴结组织结构的变化与年龄及其解剖位置有关。

英文摘要：

To investigate the changes of and histological characteristics of yak lymph nodes during developmental processes,lymph node samples from different anatomical sites （i.e. mesenterie andmandibular）in newborn,one-year-old and adult yarks were selected,and thehisto]ogical characteris- tics were observed and analyzed by using histological and statistical methods. In result,in newborn yaks,both primary and secondary lymphoid follicles were observed in lymph nodes,but only secondary lymphoid follicles were found in the one-year-old and adult groups. The number of germinal centers within unit area and the percentage of relative cortical area in lymph nodes presented the same trend, which increased from newborns to one-year-old yaks and declined from one-year-old yaks to adults,the difference among three groups was significant （P〈0.05）. However,the trend of the percentage of relative medullary area in lymph node was contrary to that of the relative cortical area,and the difference among three groups was also significant （P〈0.05）. The number of germinal centers in mandibular lymph no- des at one-year old and adult yaks were significantly higher than that in mesenteric lymph nodes（P〈 0.05）,but it was not observed in newborn yaks. The relative cortical area in mandibular lymph nodes were significantly higher than that in mesenteric lymph nodes（P〈0.05）. However,the relative medullary area in mandibular lymph nodes were significantly lower than that in mesenteric lymph nodes （P〈0.05）.In conclusion,the germinal center in lymph nodes formed at the early postnatal period in yak,and the histological structure of lymph nodes showed difference during developmental processes,which was also associated with anatomical position.