Human Reproduction Functions: Evaluation with Radiobioassay
Fuad S. Ashkar, Lelio G. Colombetti in Radiobioassays, 2019
Years before menopause occurs, the ovary shows a decrease in responsiveness to gonadotropins.60 Folliculogenesis starts to wane with a concomitant drop in ovarian estrogen production, specifically estradiol. FSH and LH elevate with a higher rise in FSH. Therefore the ratio of LH/FSH becomes greater than 1. Levels of FSH greater than 40 MIU/mℓ are conclusive in diagnosing ovarian failure. Usually there is a lag period between the FSH and the LH rise, so one can see premenopausally an FSH level greater than 40 MIU/mℓ with a normal LH level. An FSH of about 130 MIU/mℓ and an LH of about 100 MIU/mℓ is in the typical menopausal woman with an FSH/LH ratio greater than 1. A radiobioassay for LH and FSH is all that is needed for the diagnosis of menopause. The advent of the RIA techniques helped assess the hormonal patterns during the menopausal years. The findings that follow are now established.
Menstrual Endocrinology and Pathology: Caffeine, Physiology, and PMS
Barry D. Smith, Uma Gupta, B.S. Gupta in Caffeine and Activation Theory, 2006
During the follicular phase of the menstrual cycle, folliculogenesis ensues. It begins when a primordial follicle is recruited into a pool of developing follicles and typically terminates with ovulation (Khan–Sabir & Carr, 2004). Once menses begins, FSH levels decline due to the negative feedback of estrogen and the negative effects of inhibin produced by the developing follicle (Sawetawan et al., 1996; Tsafriri, 1994). FSH activates the aromatase enzyme in granulosa cells, which converts androgens to estrogen (Khan–Sabir & Carr, 2004). A decline in FSH levels leads to the production of a more androgenic microenvironment within adjacent follicles, contributing to the growth of a dominant follicle. The granulosa cells of the growing follicle also secrete a variety of peptides that may play an autocrine/paracrine role in the inhibition of development of the adjacent follicles.
Regulation of Reproduction by Dopamine
Nira Ben-Jonathan in Dopamine, 2020
A fully grown oocyte is tightly surrounded by compact layers of specialized granulosa cells (cumulus cells), forming a cumulus–oocyte complex. The process of meiosis resumption requires integration of endocrine, paracrine and autocrine signaling pathways involving interactions between the oocyte and the surrounding granulosa and cumulus cells. Ovulation occurs only once the first meiotic division has completed and a secondary oocyte has been formed within the dominant follicle. As discussed in Section 10.6, the completion of oogenesis (stage 5) occurs at the time of fertilization, when the secondary oocyte completes meiosis II and produces a very large, mature haploid ovum that unites with the sperm. The different stages of oogenesis and folliculogenesis are presented in Table 10.3 and illustrated in Figure 10.11.
Vasomotor tone-associated factors and pregnancy outcomes of women who undergo in vitro fertilization
Published in Growth Factors, 2021
Yonglian Lan, Xiaokui Yang, Yu Liang, Lingling Lei, Ying Li, Shuyu Wang
Nitric oxide (NO) is a well-known endothelium-derived relaxing factor involved in the control of vasomotor tone (Hull, White, and Pearce 1994). NO has been reported to be involved in the regulation of diverse reproductive processes, such as folliculogenesis, fertilization, ovarian blood flow, ovarian follicle maturation, and embryonic growth (Zhao et al. 2010; Lee et al. 2004). Some studies have also shown that high NO levels are related to poor outcomes of implantation. For example, the NO level in follicular fluid decreases with increasing follicle size (Kim et al. 2004). High follicular NO levels are associated with advanced fragmentation of embryos, and high serum NO levels are associated with implantation failure (Lee et al. 2004). Similar to NO, prostacyclin (prostaglandin I2 [PGI2]) is another vasodilator that contributes to the maintenance of vasomotor tone. The deficient intravascular production of PGI2 is closely associated with the occurrence of preeclampsia, hypertension, and abortion (Tulppala, Viinikka, and Ylikorkala 1991; Frölich 1990; Duley et al. 2019; Benigni and Remuzzi 2000). However, the specific roles of NO and PGI2 in the pregnancy outcome of IVF-ET have not been elucidated.
Updates in diagnosing polycystic ovary syndrome-related infertility
Published in Expert Review of Molecular Diagnostics, 2023
Hélio Haddad-Filho, Jéssica A. G. Tosatti, Fernanda M. Vale, Karina B. Gomes, Fernando M. Reis
FSH acts through its receptor (FSHR) in the granulosa cells of ovarian follicles. The perfect link between FSH and its receptor is necessary to promote steroidogenesis, cellular proliferation and folliculogenesis. The FSHR gene is located at 2p16.3 consisting of 10 exons and 9 introns. The transmembrane receptor is expressed in GC and mediates FSH signal transduction through adenylate cyclase activation and elevation of intracellular cyclic adenosine monophosphate (cAMP) [92,100]. In a prospective cohort study of 240 normogonadotropic anovulatory patients (a category that includes mostly PCOS), those with FSHR genetic variation at position 2039 A > G (Asn680Ser, rs6166) had lower pregnancy rates after ovulation induction with clomiphene compared to the AA genotype [94].
Are all antral follicles the same? Size of antral follicles as a key predictor for response to controlled ovarian stimulation
Published in Journal of Obstetrics and Gynaecology, 2022
Isil Kasapoglu, Adnan Orhan, Kiper Aslan, Esra Sen, Aysenur Kaya, Berrin Avcı, Gurkan Uncu
Suboptimal response is a distinct entity and strategies that will improve oocyte yield could be found. The key question here is why these patients have suboptimal response and what will change the suboptimal response to normal. As the pathophysiology explaining suboptimal response is not fully understood, a genotype –based mechanism suggested (Alviggi et al. 2015). A common LH beta subunit variant was associated with increase FSH consumption and suboptimal response (Alviggi et al. 2013). As the importance of LH during folliculogenesis and recruitment is known (Raju et al. 2013), this mechanism could explain decreased recruitment and response to COH, although these patients have normal serum AMH levels which reflects primordial follicle pool. So, patients with low number of recruited 2–5 mm follicles could benefit from strategies that could improve recruitment. Among these, using aromatase inhibitors or LH in the early follicular phase could improve recruitment benefiting from the androgenic effect as the androgens play critical roles on folliculogenesis (Sen et al. 2014). As the follicles with a diameter of 2 mm could respond to FSH stimulation, the increase in the FSH starting dose might be also an option in women who show hypo-sensitivity to gonadotropin stimulation in a previous cycle. Also reported studies show that when a higher starting dose of FSH given during COS, the response was not significantly influenced by the presence of FSH receptor polymorphism (Genro et al. 2012).
Related Knowledge Centers
- Menstrual Cycle
- Ovarian Follicle
- Ovary
- Ovulation
- Puberty
- Somatic Cell
- Spermatogenesis
- Oocyte
- Menopause
- Follicular Atresia