Abstract: The variations of scapular (including interseapular and subscapular) brown adipose tissue(BAT) in weight and histology withseason and body weight were studied in plateau pika (Ochotona curzoniae)androot vole(Microtus oeconomus)，at Haibei Alpine Meadow Ecosystem Research Station at an altitude of about 32O0 meters at Menyuan，Qinghai Province，from May of 1987 to July，1988．Plateau pikas and root voles were caught each month and their relativeweight of BAT (mass of BAT as a percentage of
total BW^0.73)were caculated and some monthsample wereused to make sections for light and electron microscopic investigations.The main results areas follows:
1．The relative weight of BAT decreased with increasingbody weight in growing and developing period in both O.curzoniae and M.cocomus.It has a inversely relationship between BAT weight and body weight．
2．Seasonal changes in the relative weight of BAT were inversely related to seasonal changes in ambient temperature． The relative weight of BAT was lowest in June (0.9458% W^0.73) and increased rapidly to 3．6624% W^0.73 in January in O．curzoniae．Similarly，M.oeconomus had their lowest value of relative weight of BAT in June (O.6829% W^0.73)and increased to 2.3976% W^0.73 in December． The average relative weight of BAT in O．curzoniae is higher than that 0f in M.oeconomus(2．1163 W^0.73and 1．4268 W^0.73。respectively)． Both species showed an increasing in the amount of this tissue when weather became cold in late autumn．
3．Both the histological and ultrastructural changes in BAT have a significant seasonal variations． In the summer the BAT cells have large fat droplets and have many small fat droplets during cold Winter. Theseasonal changes of milochondria sizes in BAT cell isSep．>Dec．> Mar．>Jun．in O．curzoniae and Dec．>Sept.≥Jun．> Mar．in M.oeconomus;and the cristae numbers of BAT mitochondriais Dec．≥Mar．> Jun．>Sept．in O．curzoniaeand Dec．≥Mar．>sept．>Jun. in M.oeconomus．
The results indicated that BAT is related to the requirement of the rmogenesisfor cold．In these two native speciesof small mammals the thermogenesis requiremcnt for cold are presentthroughout the year and have significant seasonalvariations.BAT and NST may be important in thermoregulation and surviva1 for nonhibernating sma1l mammals
living in cold Alpine Meadow Ecosystem．

Key words: Plateau pika, Root vole, Brown adipose tissue, Mitochondria, cristae

摘要： 本文研究了高寒草甸生态系统中两种非冬眠草食性哺乳动物一一高原鼠兔和根母鼠的褐色脂肪组织(BAT)的重量和显微结构的季节性变化，结果表明严寒季节BAT增多，BAT细胞中的脂肪滴小而多、线粒体增大及嵴数目增多，温暖季节较低，这些变化与产热需要有关。

关键词: 高原鼠兔, 根田鼠, 褐色脂肪组织, 线粒体, 嵴