Xenotransplantation: a new paradigm for human meiosis

描述（由申请人提供）：女性的生育力是多个分子途径的产物，这些分子途径始于胚胎发生期间，涉及生殖细胞进入减数分裂，以及导致原始卵泡形成的卵巢结构重组。这些事件在妇女中知之甚少，因为很难获得胎龄较晚的胎儿卵巢样本。了解这些事件的重要性是强调观察减数分裂是非常容易出错的妇女，70%的怀孕损失是由于母体减数分裂I错误。虽然已经进行了一些有限的分析，在早期减数分裂前期I的人胎儿卵母细胞，它一直很难检查后期阶段的前期I和进入dictyate逮捕发生在出生的时候，并触发了重要的结构变化，在发展中的卵巢。为了克服这些困难，R21申请试图建立一种新的异种移植系统，用于分析人类减数分裂和卵巢发育。目的一：建立人胚胎卵巢与不同免疫功能低下小鼠的异种移植方法，优化异种移植的建立条件。将通过一系列免疫组织化学和细胞遗传学标准评估异种移植物的细胞活力和发育。在目标2中，我们将研究异种移植的人类卵母细胞通过前期I的进展，利用我们在哺乳动物减数分裂方面的重要专业知识来分析同源染色体相互作用，重组动力学和交叉形成。在目标3中，我们将研究人类卵母细胞中的网状细胞阻滞的发生，以确定基质重组和原始卵泡形成过程中的分子/细胞事件。该模型为研究卵巢发育提供了一个新的范例，卵巢发育是一个知之甚少的过程，但其中的缺陷可能导致与其他哺乳动物相比，在女性中观察到的高非整倍体率，卵巢早衰和其他影响女性的生育问题。

DESCRIPTION (provided by applicant): Fertility in women is a product of multiple molecular pathways that start during embryogenesis and involve the entry of germ cells into meiosis, together with the structural reorganization of the ovary that results in primordial follicle formation. These events are poorly understood in women because of the difficulty in obtaining fetal ovarian samples of later gestational ages. The importance of understanding these events is underscored by the observation that meiosis is highly error-prone in women, with 70% of pregnancy losses being due to maternal meiosis I errors. While some limited analysis has been performed on human fetal oocytes during early meiotic prophase I, it has been hard to examine later stages of prophase I and the entry into dictyate arrest which occurs at around the time of birth and which triggers the important structural changes within the developing ovary. To overcome these difficulties, this R21 application seeks to establish a novel xenotransplantation system for analyzing human meiosis and ovarian development. In aim 1, we will establish the xenografting methodology using human fetal ovaries and different immunocompromised mouse hosts, to optimize the conditions for xenograft establishment. Xenografts will be assessed for cell viability and development by an array of immunohistochemical and cytogenetic criteria. In aim 2, we will examine the progression of xenotransplanted human oocytes through prophase I, taking advantage of our significant expertise in mammalian meiosis to analyze homologous chromosome interactions, recombination dynamics and crossover formation. In aim 3, we will examine the onset of dictyate arrest in human oocytes to define the molecular/cellular events during stromal reorganization and primordial follicle formation. This model provides a new paradigm for studying ovarian development, a poorly understood process, but defects in which may contribute to the high aneuploidy rates observed in women compared to other mammals, premature ovarian failure and other fertility issues affecting women.