Mammalian Gonadogenesis, Folliculogenesis and Fertilization

小鼠卵巢作为一个范例， 研究哺乳动物的发育生物学 性腺发生、卵子发生和受精。 1.性腺发生： 小鼠妊娠期超过20天。生殖细胞，首次发现于 发育中的胚胎在交配后7.5天（DPC）， 尿囊到生殖嵴在XX雌性中，原始性腺 13 dpc分化为形态上不同的子房。 从分离的雌性和雄性生殖嵴中纯化Poly（A+） 12-13 dpc。已经为每种性别制作了cDNA文库， 来自每个文库的随机克隆的表达序列标签具有 与现有数据库进行比较。性腺或 性别特异性基因正在进行分子和基因评估。 2.卵子发生：由三种糖蛋白组成的透明卵细胞 (ZP1、ZP 2、ZP 3）是卵巢特异性细胞外基质， 围绕着生长中的卵母细胞。我们克隆了三个老鼠基因 并证明了它们的坐标表达式是受限制的 到卵母细胞大约200 bp上游的开始， 三个转录因子基因中的每一个的转录是一个结合位点， 新的性腺特异性碱性螺旋-环-螺旋转录因子， FIG（Factor In the Gonad，alpha）克隆和鉴定 FIG基因编码的研究提供了深入了解 卵母细胞特异性基因表达的基础。 3.受精：The 分泌三种蛋白质并形成细胞外基质 介导相对物种特异性的受精事件。 为了评估蛋白质-蛋白质相互作用的组装， 我们已经建立了体外培养系统， 表达每一种peptide蛋白，并已开发出转基因 缺乏某种特定蛋白质或表达人类 同源物育种研究和体外精卵结合研究 正在被用来研究单个的蛋白质在 聚合物基质的组装，并确定分子 受精特异性的基础。

The mouse ovary serves as a paradigm for investigating the developmental biology of mammalian gonadogenesis, oogenesis and fertilization. 1. Gonadogenesis: Mouse gestation occurs over 20 days. Germ cells, first detected in the developing embryo 7.5 days post coitus (dpc), migrate from the allantois to the genital ridge. In XX females, the primitive gonad differentiates into a morphologically distinct ovary by 13 dpc. Poly(A+) was purified from female and male genital ridges isolated 12-13 dpc. cDNA libraries have been made for each sex and expressed sequence tags from random clones from each library have been compared to each other and to existing databases. Gonad or sex-specific genes are being molecularly and genetically evaluated. 2. Oogenesis: The zona pellucida, composed of three glycoproteins (ZP1, ZP2, ZP3), is an ovary- specific extracellular matrix that surrounds growing oocytes. We have cloned the three mouse genes and have demonstrated that their coordinate expression is restricted to oocytes. Approximately 200bp upstream of the start of transcription of each of the three zona genes is a binding site for a novel, gonad-specific basic helix-loop-helix transcription factor, FIG (Factor In the Gonad, alpha). The cloning and characterization of the gene encoding FIG has provided insight into the molecular basis for oocyte-specific gene expression. 3. Fertilization: The three zona proteins are secreted and form an extracellular matrix that mediates the relatively species-specific events of fertilization. To assess protein- protein interactions in the assemblage of the zona matrix, we have established in vitro culture systems that express each of the zona proteins and have developed transgenic mice that either lack a particular zona protein or express the human homologue. Breeding studies and in vitro sperm-egg binding studies are being used to investigate the role of individual zona proteins in the assemblage of the zona matrix and to determine the molecular basis for the specificity of fertilization.