Molecular control of oogenesis

Abstract

Oogenesis is a complex process regulated by a vast number of intra- and extra-ovarian factors. Oogonia, which originate from primordial germ cells, proliferate by mitosis and form primary oocytes that arrest at the prophase stage of the first meiotic division until they are fully-grown. Within primary oocytes, synthesis and accumulation of RNAs and proteins throughout oogenesis are essential for oocyte growth and maturation; and moreover, crucial for developing into a viable embryo after fertilization. Oocyte meiotic and developmental competence is gained in a gradual and sequential manner during folliculogenesis and is related to the fact that the oocyte grows in interaction with its companion somatic cells. Communication between oocyte and its surrounding granulosa cells is vital, both for oocyte development and for granulosa cells differentiation. Oocytes depend on differentiated cumulus cells, which provide them with nutrients and regulatory signals needed to promote oocyte nuclear and cytoplasmic maturation and consequently the acquisition of developmental competence.The purpose of this article is to summarize recent knowledge on the molecular aspects of oogenesis and oocyte maturation, and the crucial role of cumulus-cell interactions, highlighting the valuable contribution of experimental evidences obtained in animal models. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

Effects of in vitro growth culture duration and prematuration culture on maturational and developmental competences of bovine oocytes derived from early antral follicles

“…The lower nuclear maturation rate of 10-day IVG oocytes might have been 11 caused by insufficient growth (approximately 110 μm in diameter). Meiotic 12 competence of bovine oocytes is obtained gradually during folliculogenesis [14,28]. 13…”

“…The lower nuclear maturation rate of 10-day IVG oocytes might have been 11 caused by insufficient growth (approximately 110 μm in diameter). Meiotic 12 competence of bovine oocytes is obtained gradually during folliculogenesis [14,28]. oocytes were subjected to 20 h of pre-IVM culture with IBMX (PDE inhibitor), 20 nuclear maturation rates of 12-and 14-day IVG oocytes after IVM were significantly 21 improved to more than 70%.…”

Effect of high-fat diet-induced obesity on the Akt/FoxO/Smad signaling pathway and the follicular development of the mouse ovary

“…BMP15 is a growth factor specifically secreted from oocytes, which is important for promoting follicular development (13)(14)(15)(16)(17)(18). GC is one of the target cells of BMP15 (19,20).…”

Maximum‐likelihood approaches reveal signatures of positive selection in BMP15 and GDF9 genes modulating ovarian function in mammalian female fertility

“…In this milieu, the intra‐ovarian paracrine communications are important in oocyte development and follicle evolution and maturation and provide the tolerable sensitivity to gonadotrophic inducement. The molecular machinery is necessary during oogenesis in oocyte preparation to support embryonic development (Sánchez & Smitz, 2012). However, the oocyte development within the follicular structure involves uninterrupted two‐way dialogs between the oocyte and cumulus complex, as well as the other somatic cells in the follicles, such as the granulosa and theca cells (Wigglesworth et al., 2013).…”