Objective: To investigate the relationship between the renin-angiotensin system (RAS) and steroidogenesis during the follicular development and atresia.rn Methods: A dual-chamber culture system was prepared. Porcine ovarian follicles were divided into healthy and atretic groups. Granulosa and thecal cells were isolated, and cultured with gonadotropin in the dual-chamber system. After 48 hours, angiotensin II (Ang II), renin activity, estrodiol(E2)， progesterone(P) and testosterone(T) in the media were determined by radioimmunoassay (RIA). The follicular fluid was aspirated from both the healthy follicles and the atretic follicles, and all the hormonal levels were measured as well. The immunohistochemistry method was employed for observing the location of Ang II in follicles.rn Results: The Ang II levels increased significantly in the atresia follicles, either in follicular fluid or in the medium of cultured thecal cells. At the same time the renin activity levels decreased markedly. No significant change in the levels of both Ang II and renin activity was found in the medium of cultured granulosa cells. The productions of E2, P, T decreased in the atresia follicles, either in follicular fluid or in the media of cultured granulosa and thecal cells.rn Conclusions: The follicular atresia was related to high levels of Ang II. At the same time the level of renin activity was declined, it may be resulted from the feedback mechanism in the ovarian RAS. The arise of Ang II was found in thecal cells specially, the reason could be due to an abundance of blood vessels in the thecal cell layer, but not in the granulosa layer. E2， P， T may play very important roles in the follicle development and atresia. The results of immunohistochemistry showed an increase of Ang II levels in the atresia group, which was consistence with the RIA results.%目的：研究在卵泡发育和闭锁过程中，卵巢的肾素-血管紧张素系统(RAS)及其与甾体激素生成的相互作用。方法：制备人胎盘羊膜双池培养系统，分离了猪卵巢颗粒细胞和卵泡膜细胞，并分为健康和闭锁两组，在促性腺激素刺激下协同培养。48 h后应用放射免疫测定法(RIA)测定两种细胞培养液中的血管紧张素II(Ang II)、肾素活性、雌二醇(E2)、孕酮(P)以及睾酮(T)水平。收集健康和闭锁卵泡的卵泡液同时进行上述各项指标的测定。并运用免疫组化染色方法对健康和闭锁卵泡的Ang II定位进行了观察。结果：卵泡在闭锁状态下的Agn II水平在卵泡液中以及卵泡膜细胞培养液中均显著升高，肾素活性水平明显下降；颗粒细胞培养液中两项指标均无明显改变。闭锁卵泡的卵泡液、颗粒细胞和卵泡膜细胞培养液中的E2水平均显著下降；P、T水平也有不同程度的降低。结论：卵泡闭锁与高浓度Ang II相关，而活性肾素水平的降低可能反映了RAS中存在自身的反馈调节机制。RAS的变化主要发生在卵泡膜细胞，可能与卵泡膜细胞层具有丰富的血管而颗粒细胞层中无血管有关。E2、P、T具有不同程度的促进卵泡发育和抑制闭锁的作用。免疫组化显示闭锁卵泡中Ang II水平的升高与激素测定结果相一致。
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