Selection mechanism for ovulatory follicles in the rat ovary

为了阐明GnRH对卵巢功能的影响，采用原位杂交法检测了成年大鼠卵巢中GnRH受体的表达。GnRH受体mRNA主要在大多数卵泡和黄体细胞的颗粒细胞中检测到。闭锁卵泡颗粒细胞在其变性过程中表现出非常高水平的mRNA表达。成熟卵泡壁粒细胞中也检测到强烈的杂交信号。新形成的黄体在黄体细胞中表现出中等强度的信号，而老的黄体细胞表现出较弱的信号。在新生大鼠卵巢中，直到5日龄才检测到显著的GnRH受体mRNA信号。在10日龄间质细胞中首次观察到表达。15日龄时，该受体mRNA在大多数窦前和早期卵泡颗粒细胞中表达，而在卵母细胞和卵泡细胞中未检测到杂交信号。目前研究发现，GnRH受体mRNA在闭锁和成熟卵泡中表达，支持了GnRH在诱导大鼠卵巢卵泡闭锁和排卵中的作用。

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.