Selection mechanism for ovulatory follicles in the rat ovary

为探讨促性腺激素释放激素（GnRH）对卵巢功能的影响，采用原位杂交技术研究了GnRH受体在成年大鼠卵巢中的表达。GnRH受体mRNA主要表达于大多数卵泡的颗粒细胞和黄体细胞。闭锁卵泡颗粒细胞在其整个退化过程中表达水平很高。在成熟卵泡的壁颗粒细胞中也检测到较强的杂交信号。新形成的黄体在黄体细胞中显示中等强度的信号，而老的黄体显示较弱的信号。在新生大鼠卵巢中，直到5日龄才检测到显着的GnRH受体mRNA信号。在10日龄时首次在间质细胞中观察到表达。15日龄时，大多数腔前卵泡和早期腔卵泡的颗粒细胞中有受体mRNA表达，而卵母细胞和卵泡膜细胞中未检测到杂交信号。GnRH受体mRNA在闭锁卵泡和成熟卵泡中均有表达，支持GnRH在大鼠卵巢中诱导卵泡闭锁和排卵的假定作用。

To clarify the effect of GnRH on ovarian function, the expression of GnRH receptor in adult rat ovary was examined by in situ hybridization. GnRH receptor mRNA was detected mainly in the granulosa cells of most follicles and luteal cells. The granulosa cells of atretic follicles showed a very high level of the mRNA expression throughout their degenerating process. Strong hybridization signals were also detected in the mural granulosa cells of mature follicles. Newly formed corpora lutea exhibited signals with moderate intensity in the luteal cells, and the older ones showed weaker signals. In neonatal rat ovaries, no significant GnRH receptor mRNA signals were detected until 5 days of age. The expression was first observed at 10 days of age in the interstitial cells. At 15 days of age, the recptor mRNA was expressed in the granulosa cells of most preantral and early antral follicles, while no hybridization signals were detected in oocyte and and theca cells. The present findings that GnRH receptor mRNA was expressed in atretic and mature follicles support the putative roles of GnRH in the induction of follicular atresia and ovulation in rat ovaries.