Teleost Oogenesis and Oocyte Growth

这一建议中考察的生殖细胞发育的两个主要方面是：a)卵子发生本身(卵原细胞转变为卵母细胞)和早期卵母细胞发育；b)卵黄发生的启动。海豚和海马都将被使用，因为它们卵巢中发育卵泡的独特安排，观察到卵母细胞发育的顺序模式。这种模式始于卵巢的一侧，随着发育年龄的增加，卵泡的梯度延伸到另一侧。大多数脊椎动物胚胎卵巢中卵母细胞形成的早期事件的调节以及许多物种的成年卵巢中缺乏非常早期的卵母细胞，人们对此知之甚少。生发组织(卵原细胞和减数分裂卵母细胞)的存在使这些硬骨鱼成为研究成年脊椎动物早期生殖细胞事件及其激素调节的理想选择。卵原细胞增殖的程度和卵母细胞减数分裂进展的时间将在体内确定。然后，塞尔曼博士将尝试在体外复制这两个过程，方法是检查不同激素和共同培养的组织对卵原细胞分裂的影响，以及卵母细胞从细线期到双线期的进展。还将检查卵泡形成的过程。塞尔曼博士打算描述合并体从黄体发生前期到卵黄发生的转变，并将阐述导致卵黄发生启动的细胞机制(S)。为此，她将研究卵泡血管化、卵黄蛋白原可及性、功能性卵黄蛋白原受体的个体发育以及内化的卵黄蛋白原在卵细胞内的命运。将在体内和体外进行研究，以确定正常溶酶体合成和/或活性的停止或内吞途径的改变是否区分卵黄形成前和卵黄形成前的卵母细胞。

The two major aspects of germ cell development examined in this proposal are: a) oogenesis per se (the transformation of oogonia into oocytes) and early oocyte development and b) the initiation of vitellogenesis. Both the pipefish, Syngnathus scovelli, and the seahorse, Hippocampus erectus, will be used because of the unique arrangement of developing follicles in their ovaries, where a sequential pattern of oocyte development is observed. This pattern begins on one side of the ovary and a gradient of follicles of increasing developmental age extends to the opposite side. Little is known about the regulation of early events of oocyte formation in embryonic ovaries of most vertebrates and the absence of very early stage oocytes in adult ovaries in many species. The presence of germinal tissue (oogonia and meiotic oocytes) in a restricted but easily accessible region of syngnathan ovaries makes these teleost ideal for studying early germ cell events and their hormonal regulation in an adult vertebrate. The extent of oogonial proliferation and the time for progression of oocytes through meiosis will be determined in vivo. Dr. Selman will then attempt to duplicate both processes in vitro by examining the influence of various hormones and co- cultured tissues on oogonial division and the progression of oocytes from leptotene up to diplotene stages. The process of follicle formation will also be examined. Dr. Selman intends to characterize the transition from previtellogenesis to vitellogenesis in syngnathans and will address the cellular mechanism(s) responsible for the initiation of vitellogenesis. For this she will examine follicular vascularization, vitellogenin accessibility, the ontogeny of functional vitellogenin rectors and the intraoocytic fate of internalized vitellogenin. Studies will be performed both in vivo and in vitro to determine whether a cessation of normal lysosomal synthesis and/or activity or a modification of the endocytic pathway distinguishes previtellogenic form vitellogenic oocytes.