FSH和LH的作用

卵泡是卵巢内分泌和生殖的基础单位，是不可再生的组织，其数量和消耗的速度决定了生殖潜能和生育期限。出生后的卵泡由初级卵母细胞和颗粒细胞组成，根据卵母细胞的大小和颗粒细胞的形态和数量可分为：始基卵泡；初级卵泡；次级卵泡。次级卵泡构成了窦前卵泡池，依赖于卵泡刺激素（FSH）的卵泡募集开始于此。

Roles of FSH and LH in follicle development

The initial development of primordial follicle is independent of gonadotropin. Growth differentiation factor-9 （GDF9） and bone morphogenetic protein 15 （BMP15） produced by oocyte are essential to the development of primordial follicles, which are involved in the shift of primary follicle to growing follicles. In addition, the binding of Kit ligand （produced by granular cells） to Kit receptor （produced by oocyte and theca cells） is also essential to trigger follicular development. Gonadotropin is required for the development of secondary follicles. FSH above threshold level is key for follicular recruitment in each cycle. The production of androgen in theca cells stimulated by LH is the important source of estrogen synthesized by granular cells. Paracrine and autocrine play their roles by directly or indirectly regulating the sensitivity of follicles to FSH and LH. With the regulation of FSH, LH, paracrine and autocrine, single follicular development and ovulation in natural cycle are achieved.