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Ultrasonographic Monitoring of Follicle Growth in Controlled Ovarian Hyperstimulation
Published in Arianna D'Angelo, Nazar N. Amso, Ultrasound in Assisted Reproduction and Early Pregnancy, 2020
Follicular phase occurs at the beginning of each cycle, when a group of the most mature follicles (also known as “antral follicles”) are recruited. This phase usually lasts 6–8 days. During this phase, the follicles most sensitive to follicle-stimulating hormone (FSH) undergo further development, producing estradiol (E2) and inhibin B while the remaining follicles become atretic. This phase is followed by the ovulatory phase that occurs in midcycle. The E2 produced by the dominant follicle triggers through a positive feedback mechanism the massive release of the luteinizing hormone (LH) by the pituitary gland. The LH surge triggers ovulation within 34–38 hours. The wall of the preovulatory follicle is broken, and the oocyte is rapidly released. In the last phase known as the luteal phase, the corpus luteum secretes both E2 and progesterone, resulting in a negative feedback mechanism that suppresses the FSH release until the next menstruation. The fall in the level of circulating progesterone causes menstruation in the absence of fertilization, embryo implantation, and human chorionic gonadotropin (hCG) secretion. This physiological process is described in Figure 8.1.
Anatomy and physiology
Published in Suzanne Everett, Handbook of Contraception and Sexual Health, 2020
There are four main hormones which are the principal regulators of the female reproductive system. Follicle-stimulating hormone (FSH) stimulates follicle development and oestrogen production.Luteinizing hormone (LH) stimulates the release of the ovum.Oestrogen prepares the body and uterus for ovulation and pregnancy. Responsible for growth of body, sex organs, secondary sex characteristics, prepares the endometrium for pregnancy, makes cervical mucus thinner and more alkaline.Progesterone prepares the body for pregnancy by maintaining the endometrium when pregnancy occurs. It stimulates the development of lobules and alveoli in the mammary glands. Premenstrual water retention is attributed to progesterone, and it causes a slight rise in basal body temperature during luteal phase following ovulation.
The female reproductive system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
To understand the abnormalities that underlie menstrual disturbances, it is important to have a basic concept of the menstrual cycle (Figure 15.8). The first (follicular) phase involves the development of ovarian follicles as a result of stimulation by follicle-stimulating hormone (FSH). The fundamental features of this development are proliferation of granulosa cells, followed by formation of a space (antrum), thinning of the overlying ovarian cortex, and then – as a result of a surge in luteinizing hormone (LH) secretion – ovulation. The granulosa cells secrete oestrogen which stimulates proliferation of the endometrium (proliferative phase). After ovulation, the follicle collapses and the granulosa cells transform into luteal cells (luteal phase). The structure formed from this transformation is the corpus luteum, which secretes progesterone, leading to secretory transformation of the endometrium (secretory phase). This phase starts with subnuclear vacuolation of endometrial epithelial cells. This is followed by supranuclear vacuolation and then the appearance of intraluminal secretion. The corpus luteum has a finite lifespan and, after approximately 14 days, begins to degenerate. Progesterone support is therefore removed from the endometrium, which undergoes necrosis. The superficial endometrium is shed, leading to menstrual flow (menstrual phase). The basal endometrium, which does not respond to oestrogen and progesterone, remains and forms the base for the next menstrual cycle.
Influences of ovarian hormones on physiological responses to cold in women
Published in Temperature, 2022
Andrew M. Greenfield, Nisha Charkoudian, Billie K. Alba
While the roles of estrogens and progesterone are more thoroughly described, follicle stimulating hormone (FSH) may also influence BAT thermogenesis. FSH is a gonadotropic hormone produced by the anterior pituitary gland that stimulates the growth of ovarian follicles [176]. FSH begins to rise at the end of the luteal phase and continues in the early follicular phase, with a rapid rise in the pre-ovulatory phase [177]. In rodents, FSH influences energy metabolism by stimulating adipocyte lipid biosynthesis [178]. Interestingly, there is new evidence to suggest that FSH negatively regulates BAT thermogenesis, such that FSH blockade increases BAT activation and thermogenesis in mice [179]. This finding is supported by data demonstrating that FSH inhibits adipocyte UCP1 expression through reduced cAMP signaling [180]. However, no mechanistic studies examining FSH in humans with regard to BAT or thermoregulation have been performed. Therefore, significant research questions remain to whether there is a potential modulation of thermoregulatory function by FSH across the menstrual cycle.
Efficacy and safety of follitropin alpha biosimilars compared to their reference product: a Meta-analysis
Published in Gynecological Endocrinology, 2021
Maria Cristina Budani, Stefania Fensore, Marco Di Marzio, Gian Mario Tiboni
Concerning the ovarian follicle development, follicle-stimulating hormone (FSH) is a gonadotrophic hormone produced by the anterior lobe of the pituitary gland [3]. FSH is a heterodimeric glycoprotein that consists of two distinct subunits, α and β. The α-subunit is common to all pituitary and placental glycoprotein hormones whereas the β-subunit is hormone-specific and the heterodimer confers biological activity [4]. Controlled ovarian stimulation (COS) for assisted reproductive technology (ART) is initiated and maintained through the exogenous administration of gonadotropins. Available exogenous FSH formulations include: highly purified human menopausal gonadotropin (hMG) obtained by extraction and purification from urine of menopausal women, highly purified human urinary FSH (u-hFSH) obtained by extraction and purification from human urine and recombinant FSH (r-FSH) obtained with recombinant technology [5].
Ameliorative effects of quercetin on folliculogenesis in diabetic mice: a stereological study
Published in Gynecological Endocrinology, 2020
Ayeh Bolouki, Fatemeh Zal, Hossein Bordbar
The ovarian follicles contain a single immature oocyte. There are five major types of follicles including primordial, primary, secondary, antral, and mature Graafian. In the primordial follicles, primary oocytes are enclosed within single squamous or cubical epithelial cells. In the primary follicles, the oocytes are covered by cuboidal epithelial cells. Secondary follicles class possess more than one layer of granulosa cells with no visible antrum. Antral follicles possess a single large antral space. Ultimately, Graafian follicles, the most enlarged follicles consist of cumulus oophorus, corona radiate, and a large antrum. Also, corpora lutea were defined as developing from the Graafian follicles following ovulation. Moreover, there are many atretic follicles undergoing degeneration before or after the maturity in the ovarian slices [12].