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The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the uterus (womb) to receive an embryo. These cycles are concurrent and coordinated, normally last between 21 and 35 days, with a median length of 28 days, and continue for about 30–45 years.
Luteinizing hormone is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. In females, an acute rise of LH known as an LH surge, triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell–stimulating hormone (ICSH), it stimulates Leydig cell production of testosterone. It acts synergistically with follicle-stimulating hormone (FSH).
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and luteinizing hormone (LH) work together in the reproductive system.
The corpus luteum is a temporary endocrine structure in female ovaries involved in the production of relatively high levels of progesterone, and moderate levels of estradiol, and inhibin A. It is the remains of the ovarian follicle that has released a mature ovum during a previous ovulation.
Gonadotropins are glycoprotein hormones secreted by gonadotropic cells of the anterior pituitary of vertebrates. This family includes the mammalian hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the placental/chorionic gonadotropins, human chorionic gonadotropin (hCG) and equine chorionic gonadotropin (eCG), as well as at least two forms of fish gonadotropins. These hormones are central to the complex endocrine system that regulates normal growth, sexual development, and reproductive function. LH and FSH are secreted by the anterior pituitary gland, while hCG and eCG are secreted by the placenta in pregnant humans and mares, respectively. The gonadotropins act on the gonads, controlling gamete and sex hormone production.
Ovarian hyperstimulation syndrome (OHSS) is a medical condition that can occur in some women who take fertility medication to stimulate egg growth, and in other women in very rare cases. Most cases are mild, but rarely the condition is severe and can lead to serious illness or death.
In biology, folliculogenesis is the maturation of the ovarian follicle, a densely packed shell of somatic cells that contains an immature oocyte. Folliculogenesis describes the progression of a number of small primordial follicles into large preovulatory follicles that occurs in part during the menstrual cycle.
Urofollitropin is a purified form of follicle-stimulating hormone (FSH) that is manufactured by extraction from human urine and then purified to remove various proteins and other substances. FSH is important in the development of follicles (eggs) produced by the ovaries. Given by subcutaneous injection, it is used in combination with human chorionic gonadotropin (hCG) to assist in ovulation and fertility. It is also used with in vitro fertilization methods. The dosage is adjusted to each individual's response.
Luteolysis is the structural and functional degradation of the corpus luteum, which occurs at the end of the luteal phase of both the estrous and menstrual cycles in the absence of pregnancy.
The menstrual cycle is on average 28 days in length. It begins with menses during the follicular phase, followed by ovulation and ending with the luteal phase. Unlike the follicular phase which can vary in length among individuals, the luteal phase is typically fixed at approximately 14 days and is characterized by changes to hormone levels, such as an increase in progesterone and estrogen levels, decrease in gonadotropins such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), changes to the endometrial lining to promote implantation of the fertilized egg, and development of the corpus luteum. In the absence of fertilization by sperm, the corpus luteum atrophies leading to a decrease in progesterone and estrogen, an increase in FSH and LH, and shedding of the endometrial lining (menses) to begin the menstrual cycle again.
Ovulation induction is the stimulation of ovulation by medication. It is usually used in the sense of stimulation of the development of ovarian follicles to reverse anovulation or oligoovulation.
Controlled ovarian hyperstimulation is a technique used in assisted reproduction involving the use of fertility medications to induce ovulation by multiple ovarian follicles. These multiple follicles can be taken out by oocyte retrieval for use in in vitro fertilisation (IVF), or be given time to ovulate, resulting in superovulation which is the ovulation of a larger-than-normal number of eggs, generally in the sense of at least two. When ovulated follicles are fertilised in vivo, whether by natural or artificial insemination, there is a very high risk of a multiple pregnancy.
Poor ovarian reserve is a condition of low fertility characterized by 1): low numbers of remaining oocytes in the ovaries or 2) possibly impaired preantral oocyte development or recruitment. Recent research suggests that premature ovarian aging and premature ovarian failure may represent a continuum of premature ovarian senescence. It is usually accompanied by high FSH levels.
Deslorelin, sold under the brand names Ovuplant, SucroMate, and Suprelorin among others, is an injectable gonadotropin releasing hormone superagonist which is used in veterinary medicine for various indications.
Equine chorionic gonadotropin is a gonadotropic hormone produced in the chorion of pregnant mares. Previously referred to as pregnant mare's serum gonadotropin (PMSG), the hormone is commonly used in concert with progestogen to induce ovulation in livestock prior to artificial insemination.
Gonadotropin preparations are drugs that mimic the physiological effects of gonadotropins, used therapeutically mainly as fertility medication for ovarian hyperstimulation and ovulation induction. For example, the so-called menotropins consist of LH and FSH extracted from human urine from menopausal women. There are also recombinant variants.
Hormonal regulation occurs at every stage of development. A milieu of hormones simultaneously affects development of the fetus during embryogenesis and the mother, including human chorionic gonadotropin (hCG) and progesterone (P4).
Choriogonadotropin subunit beta (CG-beta) also known as chorionic gonadotrophin chain beta is a protein that in humans is encoded by the CGB gene.
A GnRH modulator, or GnRH receptor modulator, also known as an LHRH modulator or LHRH receptor modulator, is a type of medication which modulates the GnRH receptor, the biological target of the hypothalamic hormone gonadotropin-releasing hormone. They include GnRH agonists and GnRH antagonists. These medications may be GnRH analogues like leuprorelin and cetrorelix – peptides that are structurally related to GnRH – or small-molecules like elagolix and relugolix, which are structurally distinct from and unrelated to GnRH analogues.
Gonadotropin surge-attenuating factor (GnSAF) is a nonsteroidal ovarian hormone produced by the granulosa cells of small antral ovarian follicles in females. GnSAF is involved in regulating the secretion of luteinizing hormone (LH) from the anterior pituitary and the ovarian cycle. During the early to mid-follicular phase of the ovarian cycle, GnSAF acts on the anterior pituitary to attenuate LH release, limiting the secretion of LH to only basal levels. At the transition between follicular and luteal phase, GnSAF bioactivity declines sufficiently to permit LH secretion above basal levels, resulting in the mid-cycle LH surge that initiates ovulation. In normally ovulating women, the LH surge only occurs when the oocyte is mature and ready for extrusion. GnSAF bioactivity is responsible for the synchronised, biphasic nature of LH secretion.
References
- ↑ McCue, PM (June 4, 2017). "eFSH in clinical equine practice". Theriogenology. 68 (3): 429–33. doi:10.1016/j.theriogenology.2007.04.027. PMID 17548106.
- 1 2 Raz, T.; Green, G. M.; Carley, S. D.; Card, C. E. (2011). "Folliculogenesis, embryo parameters and post-transfer recipient pregnancy rate following equine follicle-stimulating hormone (eFSH) treatment in cycling donor mares". Australian Veterinary Journal. 89 (4): 138–142. doi:10.1111/j.1751-0813.2011.00691.x. ISSN 1751-0813. PMID 21418170.
- 1 2 Hughes, Sydney; Cerny, Katheryn; Campos, Juliana; Troedsson, Mats; Ball, Barry; Squires, Edward (2014-08-01). "The Use of Equine Follicle Stimulating Hormone to Increase Equine Chorionic Gonadotropin in the Pregnant Mare". Journal of Equine Veterinary Science. 34 (8): 1021–1024. doi:10.1016/j.jevs.2014.05.003. ISSN 0737-0806.
- ↑ Logan, N.; McCue, P.; Alonso, M.; Squires, E. (2006). "365 THE EFFECT OF ADMINISTERING PROGESTERONE AND ESTRADIOL PRIOR TO eFSH ON THE SUPEROVULATORY RESPONSE OF MARES". Reproduction, Fertility and Development. 18 (2): 290. doi:10.1071/rdv18n2ab365. ISSN 1448-5990.
