Oogenesis in Women: From Molecular Regulatory Pathways and Maternal Age to Stem Cells

Abstract

It is a well-known fact that the reproductive organs in women, especially oocytes, are exposed to numerous regulatory pathways and environmental stimuli. The maternal age is one cornerstone that influences the process of oocyte fertilization. More precisely, the longer a given oocyte is in the waiting-line to be ovulated from menarche to menopause, the longer the duration from oogenesis to fertilization, and therefore, the lower the chances of success to form a viable embryo. The age of menarche in girls ranges from 10 to 16 years, and the age of menopause in women ranges from approximately 45 to 55 years. Researchers are paying attention to the regulatory pathways that are impacting the oocyte at the very beginning during oogenesis in fetal life to discover genes and proteins that could be crucial for the oocyte’s lifespan. Due to the general trend in industrialized countries in the last three decades, women are giving birth to their first child in their thirties. Therefore, maternal age has become an important factor impacting oocytes developmental competence, since the higher a woman’s age, the higher the chances of miscarriage due to several causes, such as aneuploidy. Meiotic failures during oogenesis, such as, for instance, chromosome segregation failures or chromosomal non-disjunction, are influencing the latter-mentioned aging-related phenomenon too. These errors early in life of women can lead to sub- or infertility. It cannot be neglected that oogenesis is a precisely orchestrated process, during which the oogonia and primary oocytes are formed, and RNA synthesis takes place. These RNAs are crucial for oocyte growth and maturation. In this review, we intend to describe the relevance of regulatory pathways during the oogenesis in women. Furthermore, we focus on molecular pathways of oocyte developmental competence with regard to maternal effects during embryogenesis. On the background of transcriptional mechanisms that enable the transition from a silenced oocyte to a transcriptionally active embryo, we will briefly discuss the potential of induced pluripotent stem cells.

Minerals and the Menstrual Cycle: Impacts on Ovulation and Endometrial Health

“…Female fetuses have approximately 6-7 million potential follicles; however, by puberty, only about 400,000 remain [188,189]. Each menstrual cycle then witnesses a cohort of these follicles initiating development, though usually only one reaches full maturity and undergoes ovulation [190].…”

Nanomaterials Solutions for Contraception: Concerns, Advances, and Prospects

“…Copyright 2016 Elsevier B.V. (D) Inhibition of ovulation by interfering with the hormonal regulation of the hypothalamic-pituitary-gonad. Adapted with permission under a Creative Commons CC BY 4.0 License from ref . Copyright 2023 MPDI.…”

The Relationship Between Serum Anti-Müllerian Hormone and Basal Antral Follicle Count in Infertile Women Under 35 Years: An Assessment of Ovarian Reserve

“…A girl child is born with 1-2 million primordial cells that characterize the oocyte's progenitor cells [26,43,44]. Nonetheless, females in their healthy lives suffer from a diminution of ovarian reserve, resulting in infertility and sub-fertility long before menopause, often because of diminished ovarian reserve [8,26,45,46].…”