Portrait of an oocyte: our obscure origin
Roger Gosden, Bora Lee
Roger Gosden, Bora Lee
Published April 1, 2010
Citation Information: J Clin Invest. 2010;120(4):973-983. https://doi.org/10.1172/JCI41294.
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Portrait of an oocyte: our obscure origin

Abstract

Oocytes play a pivotal role in the cycle of human life. As we discuss here, after emerging from germline stem cells in the fetus, they grow in a follicular niche in which development is harmonized for timely ovulation and hormone secretion after puberty. Most human oocytes have poor developmental competence and are peculiarly vulnerable to chromosomal malsegregation, especially as women pass the optimal years of fertility and may begin to turn to assisted reproductive technologies (ARTs) and egg donation. Research needs to focus on the molecular factors involved and the environmental niche required for optimal development of oocytes, with the aim of increasing their numbers and quality for ARTs, since these are the factors that so often limit human fertility.

Authors

Roger Gosden, Bora Lee

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Figure 1

Schematic diagram of follicle maturation in the ovary.

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Schematic diagram of follicle maturation in the ovary. Prior to birth, p...
Prior to birth, primordial germ cells migrate to the developing ovary and, after a period of proliferation, they enter meiosis I. At birth the ovary contains many primordial-stage follicles, which contain small, non-growing oocytes surrounded by a single granulosa cell layer. These follicles develop in the step-wise manner depicted to become preovulatory, Graafian-stage follicles, which contain a fully grown oocyte. Oocytes reach metaphase II of meiosis after the ovulatory surge of gonadotropins that occurs mid–menstrual cycle. Meiosis is only completed upon oocyte fertilization.