Establishment of oocyte population in the fetal ovary: Primordial germ cell proliferation and oocyte programmed cell death
Establishment of oocyte population in the fetal ovary: Primordial germ cell proliferation and oocyte programmed cell death
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DOI：
10.1016/s1472-6483(10)60939-x
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发表时间：
2005-02-01
影响因子：
4
通讯作者：
Lobascio, M
中科院分区：
文献类型：
--
作者：
De Felici, M;Klinger, FG;Lobascio, M
细胞增殖和细胞损失的严格控制对于复杂多细胞生物体中不同细胞群的协调功能是必不可少的。卵子发生的特征在于发生在胚胎-胎儿生命期间的第一阶段，并且与精子发生相同，在此期间，生殖系干细胞（原始生殖细胞（PGC））的有丝分裂增殖超过生殖细胞死亡。其结果是根据物种形成相对较高数量的生殖细胞，准备进入性别特异性分化。在雌性中，PGC进入减数分裂并成为卵母细胞，从而结束其干细胞潜能。卵母细胞在胎儿卵巢中进入减数分裂后，经过细线期、偶线期和粗线期，然后在减数分裂前期1的最后阶段，即大约出生时的双线期或网状期停止。大部分卵母细胞在胎儿期或出生后不久死亡。人们普遍认为，在哺乳动物中，雌性动物出生时卵巢内的卵母细胞数量是固定的，随着时间的推移，卵母细胞数量逐渐减少，没有更新的可能性。一旦卵母细胞储备已经耗尽，卵巢衰老，驱动什么是所谓的更年期的妇女，迅速加剧。女性的生育寿命取决于出生时卵母细胞池的大小和卵母细胞池消耗的速度。哪些机制控制PGC增殖？为什么大多数卵母细胞在胎儿期死亡，这种大规模退化的机制是什么？有没有可能通过减少胎儿期卵母细胞的损失来延长女性的寿命？这篇评论报告了一些最新的结果，试图回答这些问题。
(S)trict control of cell proliferation and cell loss is essential for the coordinated functions of different cell populations in complex multicellular organisms. Oogenesis is characterized by a first phase occurring during embryo-fetal life and in common with spermatogenesis, during which mitotic proliferation of the germline stem cells, the primordial germ cells (PGC), prevails over germ cell death. The result is the formation of a relatively high number of germ cells depending on the species, ready to enter sex specific differentiation. In the female, PGC enter into meiosis and become oocytes, thereby ending their stem cell potential. After entering into meiosis in the fetal ovary, oocytes pass through leptotene, zygotene and pachytene stages before arresting in the last stage of meiotic prophase 1, the diplotene or dictyate stage at about the time of birth. The most part of oocytes die during the fetal period or shortly after birth. It is widely accepted that in mammals a female is born with a fixed number of oocytes within the ovaries, which over the years progressively decreases without possibility for renewal. Once the oocyte reserve has been exhausted, ovarian senescence, driving what is referred to as the menopause in women, rapidly ensues. The fertile lifespan of a female depends by the size of the oocyte pool at birth and the rapidity of the oocyte pool depletion. Which mechanisms control PGC proliferation? Why do most of the oocytes die during fetal life and what are the mechanisms of such massive degeneration? Is it possible to prolong the lifespan of a female by reducing oocyte lost during the fetal life? This review reports some of the most recent results obtained in an attempt to answer these questions.