Ovulation – wikipedia symptoms of hormonal imbalance

In humans, ovulation occurs about midway through the menstrual cycle, after the follicular phase. The few days surrounding ovulation (from approximately days 10 to 18 of a 28-day cycle), constitute the most fertile phase. [3] [4] [5] [6] The time from the beginning of the last menstrual period (LMP) until ovulation is, on average, 14.6 [7] days, but with substantial variation between females and between cycles in any single female, with an overall 95% prediction interval of 8.2 to 20.5 [7] days.

The process of ovulation is controlled by the hypothalamus of the brain and through the release of hormones secreted in the anterior lobe of the pituitary gland, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). [8] In the preovulatory phase of the menstrual cycle, the ovarian follicle will undergo a series of transformations called cumulus expansion, which is stimulated by FSH.


After this is done, a hole called the stigma will form in the follicle, and the secondary oocyte will leave the follicle through this hole. Ovulation is triggered by a spike in the amount of FSH and LH released from the pituitary gland. During the luteal (post-ovulatory) phase, the secondary oocyte will travel through the fallopian tubes toward the uterus. If fertilized by a sperm, the fertilized secondary oocyte or ovum may implant there 6–12 days later. [9] Follicular phase [ edit ]

For ovulation to be successful, the ovum must be supported by the corona radiata and cumulus oophorous granulosa cells. The latter undergo a period of proliferation and mucification known as cumulus expansion. Mucification is the secretion of a hyaluronic acid-rich cocktail that disperses and gathers the cumulus cell network in a sticky matrix around the ovum. This network stays with the ovum after ovulation and has been shown to be necessary for fertilization. [12] [13]

An increase in cumulus cell number causes a concomitant increase in antrum fluid volume that can swell the follicle to over 20 mm in diameter. It forms a pronounced bulge at the surface of the ovary called the blister. [ citation needed] Ovulation [ edit ]

Estrogen levels peak towards the end of the follicular phase. This causes a surge in levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This lasts from 24 to 36 hours, and results in the rupture of the ovarian follicles, causing the oocyte to be released from the ovary. [14]

Through a signal transduction cascade initiated by LH, proteolytic enzymes are secreted by the follicle that degrade the follicular tissue at the site of the blister, forming a hole called the stigma. The secondary oocyte leaves the ruptured follicle and moves out into the peritoneal cavity through the stigma, where it is caught by the fimbriae at the end of the fallopian tube. After entering the fallopian tube, the oocyte is pushed along by cilia, beginning its journey toward the uterus. [8]

By this time, the oocyte has completed meiosis I, yielding two cells: the larger secondary oocyte that contains all of the cytoplasmic material and a smaller, inactive first polar body. Meiosis II follows at once but will be arrested in the metaphase and will so remain until fertilization. The spindle apparatus of the second meiotic division appears at the time of ovulation. If no fertilization occurs, the oocyte will degenerate between 12 and 24 hours after ovulation. [15] Approximately 1-2% of ovulations release more than one oocyte. This tendency increases with maternal age. Fertilization of two different oocytes by two different spermatozoa results in fraternal twins. [8]

Symptoms related to the onset of ovulation, the moment of ovulation and the body’s process of beginning and ending the menstrual cycle vary in intensity with each female but are fundamentally the same. The charting of such symptoms — primarily basal body temperature, mittelschmerz and cervical position — is referred to as the sympto-thermal method of fertility awareness, which allow auto-diagnosis by a female of her state of ovulation. Once training has been given by a suitable authority, fertility charts can be completed on a cycle-by-cycle basis to show ovulation. This gives the possibility of using the data to predict fertility for natural contraception and pregnancy planning.

• Anovulation is absence of ovulation when it would be normally expected (in a post- menarchal, premenopausal female). Anovulation usually manifests itself as irregularity of menstrual periods, that is, unpredictable variability of intervals, duration, or bleeding. Anovulation can also cause cessation of periods (secondary amenorrhea) or excessive bleeding ( dysfunctional uterine bleeding).

Ovulation induction is a promising assisted reproductive technology for patients with conditions such as polycystic ovary syndrome (PCOS) and oligomenorrhea. It is also used in in vitro fertilization to make the follicles mature before egg retrieval. Usually, ovarian stimulation is used in conjunction with ovulation induction to stimulate the formation of multiple oocytes. [25] Some sources [25] include ovulation induction in the definition of ovarian stimulation.

The majority of hormonal contraceptives and conception boosters focus on the ovulatory phase of the menstrual cycle because it is the most important determinant of fertility. Hormone therapy can positively or negatively interfere with ovulation and can give a sense of cycle control to the female. [ citation needed]

Estradiol and progesterone, taken in various forms including combined oral contraceptive pills, mimics the hormonal levels of the menstrual cycle and engage in negative feedback of folliculogenesis and ovulation. [ citation needed] See also [ edit ]

• ^ Nichter, Mark; Nichter, Mimi (1996). Cultural Notions of Fertility in South Asia and Their Influence on Sri Lankan Family Planning Practices. In Nichter, Mark; Nichter, Mimi. Anthropology International Health: South Asian Case Studies. Psychology Press. pp. 8–11. ISBN 9782884491716 . Retrieved 2013-11-09. CS1 maint: Uses authors parameter ( link) CS1 maint: Uses editors parameter ( link)

• ^ Depares J, Ryder RE, Walker SM, Scanlon MF, Norman CM. Ovarian ultrasonography highlights precision of symptoms of ovulation as markers of ovulation. Br Med J (Clin Res Ed). 292: 1562. doi: 10.1136/bmj.292.6535.1562. PMC 1340563 . PMID 3087519. CS1 maint: Multiple names: authors list ( link)

• ^ Navarrete-Palacios E, Hudson R, Reyes-Guerrero G, Guevara-Guzmán R (July 2003). Lower olfactory threshold during the ovulatory phase of the menstrual cycle. Biol Psychol. 63 (3): 269–79. doi: 10.1016/S0301-0511(03)00076-0. PMID 12853171.

• ^ Susan B. Bullivant; Sarah A. Sellergren; Kathleen Stern; et al. (February 2004). Female’s sexual experience during the menstrual cycle: identification of the sexual phase by noninvasive measurement of luteinizing hormone. Journal of Sex Research. 41 (1): 82–93 (in online article, see pp.14–15, 18–22). doi: 10.1080/00224490409552216. PMID 15216427. Archived from the original on July 28, 2007.

• ^ Roberts S, Havlicek J, Flegr J, Hruskova M, Little A, Jones B, Perrett D, Petrie M (August 2004). Female facial attractiveness increases during the fertile phase of the menstrual cycle. Proc Biol Sci. 271 (Suppl 5:S): 270–2. doi: 10.1098/rsbl.2004.0174. PMC 1810066 . PMID 15503991.

• ^ Dunson, D.B.; Baird, D.D.; Wilcox, A.J.; Weinberg, C.R. (1999). Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation. Human Reproduction. 14 (7): 1835–1839. doi: 10.1093/humrep/14.7.1835. ISSN 1460-2350.