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Related Concept Videos

Folliculogenesis01:20

Folliculogenesis

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Folliculogenesis is the development of ovarian follicles, the specialized structures within the ovarian cortex where oogenesis, or egg development, occurs. This process is essential for female reproductive health and begins during fetal development when primordial follicles are formed. Each primordial follicle comprises a primary oocyte in the center, surrounded by a single layer of squamous pre-granulosa cells. These follicles remain dormant in late prophase I of meiosis until triggered by...
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Oogenesis01:22

Oogenesis

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Oogenesis,  the process of developing egg cells (female gametes), occurs within the ovaries and is fundamental to female fertility. This sequence begins during fetal development when diploid oogonia in the developing ovaries undergo mitotic divisions to produce primary oocytes. By birth, these primary oocytes enter prophase I of meiosis but become arrested in this stage, remaining suspended until puberty.
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is...
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Oogenesis02:07

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In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from the equivalent procedure of spermatogenesis in males. First, meiotic divisions during oogenesis are asymmetric, meaning that a large oocyte (containing most of the cytoplasm) and minor polar body are produced as a result of meiosis I, and again following meiosis II. Since only oocytes will go on to form embryos if fertilized, this unequal...
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Hormonal Control of the Ovarian Cycle01:30

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The ovarian cycle is meticulously regulated by the hypothalamic-pituitary-gonadal axis. This cycle orchestrates the release of a mature oocyte, essential for reproduction.
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle.  At puberty, GnRH secretion increases in both frequency and...
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Ovarian Cycle01:27

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The menstrual cycle includes a critical component known as the ovarian cycle, which undergoes two main phases each month—the follicular phase and the luteal phase. The follicular phase is variable and averaging around 14 days. Ovulation, triggered by a surge in luteinizing hormone (LH), marks the transition between the two phases. The second phase, the luteal phase, is relatively consistent, lasting approximately 14 days, and is marked by the activity of the corpus luteum. While a cycle...
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Multipotency and Niche of Bulge Stem Cell01:06

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A hair follicle or HF is a small part of the skin that produces the hair shaft. Paul Gerson Unna was the first to observe a bulge in the human hair follicle's outer root sheath (ORS). The bulge is present between the sebaceous gland and the arrector pili muscle and is the niche for hair follicle stem cells (HFSCs). The bulge is also a niche for melanocyte stem cells, and their loss results in graying of hair. The HFSCs express Sox9 and Lhx2, which help them maintain stemness and prevent...
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Gene Expression Analyses in Human Follicles
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Primordial Follicle Formation - Some Assembly Required.

Jessica M O'Connell1, Melissa E Pepling1

  • 1Department of Biology, Syracuse University, Syracuse, NY, USA.

Current Opinion in Endocrine and Metabolic Research
|May 24, 2021
PubMed
Summary
This summary is machine-generated.

Mammalian germ cell nests break apart to form primordial follicles, with some oocytes acting as nurse cells. Autophagy, not just apoptosis, is crucial for oocyte survival and maintaining ovarian reserve.

Keywords:
Germ Cell CystsNest BreakdownOocyte SurvivalOvarian ReservePrimordial Follicle Formation

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Area of Science:

  • Reproductive Biology
  • Developmental Biology
  • Cell Biology

Background:

  • Germ cell nests are characteristic of mammalian oogenesis.
  • The precise mechanisms of germ cell nest breakdown and primordial follicle formation are not fully elucidated.
  • Oocyte survival during this process is critical for maintaining the ovarian reserve.

Purpose of the Study:

  • To explore the roles of nurse cells within germ cell cysts.
  • To understand the cellular interactions during germ cell nest breakdown.
  • To investigate the mechanisms of oocyte survival, including the interplay between autophagy and apoptosis.

Main Methods:

  • Review of recent research on germ cell development and follicle formation.
  • Analysis of signaling pathways, transcription factors, and RNA binding proteins involved.
  • Examination of cellular processes like apoptosis and autophagy in oocyte survival.

Main Results:

  • Evidence suggests some oocytes function as nurse cells within germ cell nests.
  • Interactions between cyst cells change as oocytes individualize and associate with pregranulosa cells.
  • Autophagy plays a significant role in counteracting apoptosis, promoting oocyte survival and preserving ovarian reserve.

Conclusions:

  • Recent studies have identified novel molecular players, including signaling molecules, transcription factors, and RNA binding proteins, that regulate primordial follicle formation.
  • Understanding these pathways is key to comprehending ovarian reserve maintenance.
  • The balance between autophagy and apoptosis is critical for successful oogenesis.