The earliest stages of follicular development: follicle formation and activation.
The earliest stages of follicular development: follicle formation and activation.
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DOI：
10.7313/upo9781907284991.018
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Muruvi W
中科院分区：
文献类型：
--
作者：
Fortune JE;Yang MY;Muruvi W
原始卵泡的形成以建立静止卵泡的储存库，并逐渐耗尽该储存库以提供一系列生长卵泡是女性生育力的关键，但对卵泡发育的这些早期阶段的调节知之甚少。这篇综述总结了我们的实验室的努力，阐明这些关键过程中的牛。原始卵泡首先出现在妊娠早期（第90天）的胎儿卵巢中，此时胎儿卵巢产生的雌二醇和孕酮减少。在90 - 120天龄胎儿的卵巢皮质中，卵泡在体外形成，雌二醇或孕酮抑制卵泡形成，而非芳香化雄激素5α-二氢睾酮（DHT）则不抑制卵泡形成。新形成的牛卵泡在体外2天内不能激活，但它们可以在更长的培养过程中获得激活能力;雌二醇和孕酮抑制它们激活能力的获得。当原始卵泡第一次在牛中形成时，它们的卵母细胞尚未处于减数分裂阻滞中，并且激活能力的获得与它们在第一前期的双线期阶段的减数分裂阻滞的进展相关。牛原始卵泡获得激活能力后，在体外可被胰岛素或kit配体刺激激活，而抗苗勒管激素（AMH）则具有抑制作用。虽然在体外很少有卵泡进展到第二阶段，但睾酮或血管内皮生长因子（VEGF）的加入显着增加了这种转变的发生率。卵泡发育的最早阶段的调节是复杂的，远未理解;更好的理解可能会导致新的干预措施，以提高生育能力。
The formation of primordial follicles to establish a reservoir of resting follicles and the gradual depletion of that reservoir to provide a succession of growing follicles are key to female fertility, but little is known about the regulation of these early stages of follicular development. This review summarizes the efforts of our laboratory to elucidate these critical processes in cattle. Primordial follicles first appear in fetal ovaries around the end of the first trimester of pregnancy (Day 90), during a decline in fetal ovarian production of estradiol and progesterone. In ovarian cortical pieces from 90 to 120-day-old fetuses, follicles form in vitro and estradiol or progesterone inhibits follicle formation, whereas the non-aromatizable androgen 5α-dihydrotestosterone (DHT) does not. Newly formed bovine follicles are not capable of activating within 2 days in vitro, but they can acquire the capacity to activate during a longer culture; estradiol and progesterone inhibit the acquisition of their capacity to activate. When primordial follicles first form in cattle, their oocytes are not yet in meiotic arrest and acquisition of competence to activate is correlated with their progression to meiotic arrest at the diplotene stage of first prophase. After they acquire the competence to activate, bovine primordial follicles can be stimulated to activate in vitro by insulin or kit ligand, whereas anti-Mullerian hormone (AMH) is inhibitory. Although few follicles progress to the secondary stage in vitro, addition of testosterone or vascular endothelial growth factor (VEGF) dramatically increased the incidence of that transition. Regulation of the earliest stages of follicular development is complex and far from understood; better understanding could lead to new interventions to enhance fertility.