Department of Biology, Syracuse University, Syracuse, New York 13244, USA.
Reproduction. 2012 Feb;143(2):139-49. doi: 10.1530/REP-11-0299. Epub 2011 Nov 7.
The differentiation of primordial germ cells (PGCs) into functional oocytes is important for the continuation of species. In mammals, PGCs begin to differentiate into oocytes during embryonic development. Oocytes develop in clusters called germ line cysts. During fetal or neonatal development, germ cell cysts break apart into single oocytes that become surrounded by pregranulosa cells to form primordial follicles. During the process of cyst breakdown, a subset of cells in each cyst undergoes cell death with only one-third of the initial number of oocytes surviving to form primordial follicles. The mechanisms that control cyst breakdown, oocyte survival, and follicle assembly are currently under investigation. This review describes the mechanisms that have been implicated in the control of primordial follicle formation, which include programmed cell death regulation, growth factor and other signaling pathways, regulation by transcription factors and hormones, meiotic progression, and changes in cell adhesion. Elucidation of mechanisms leading to formation of the primordial follicle pool will help research efforts in ovarian biology and improve treatments of female infertility, premature ovarian failure, and reproductive cancers.
原始生殖细胞（PGC）分化为功能性卵子对于物种的延续至关重要。在哺乳动物中，PGC 在胚胎发育过程中开始分化为卵子。卵子在称为生殖细胞囊泡的簇中发育。在胎儿或新生儿发育过程中，生殖细胞囊泡分裂成单个卵子，这些卵子被颗粒细胞前体细胞包围形成原始卵泡。在囊泡破裂的过程中，每个囊泡中的一部分细胞会发生细胞死亡，只有三分之一的初始卵子存活下来形成原始卵泡。目前正在研究控制囊泡破裂、卵子存活和卵泡组装的机制。本综述描述了与原始卵泡形成的控制相关的机制，包括程序性细胞死亡调节、生长因子和其他信号通路、转录因子和激素的调节、减数分裂进展以及细胞黏附的变化。阐明导致原始卵泡库形成的机制将有助于卵巢生物学的研究，并改善女性不孕、卵巢早衰和生殖癌症的治疗。
