Ovulation is the phase of menstrual cycle that involves release of an egg or ovum by a mature female ovary. It usually occurs midway during the menstrual cycle. About once in a month, an egg matures in the ovarian follicle and is released by one of the ovaries. The released egg travels through the fallopian tube and, if a male sperm happens to be present in the tube, fertilization of the egg occurs and that's how a woman conceives.
The process of ovulation is under control of a small gland in the brain called pituitary, which is in turn controlled by the hypothalamus. Hypothalamus sends signals to the pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The sudden surge in the level of these hormones triggers ovulation. Ovulation occurs between 10th and 19th day of menstrual cycle and this is the time where females are most fertile.
Phases of Menstrual Cycle:
The entire menstrual cycle is divided into three phases:
a. Periovulatory or follicular phase: The follicular phase begins with the first day of menstrual cycle and lasts about 10 to 14days. During this phase, the hypothalamus stimulates the pituitary gland to release FSH. FSH stimulates development of follicles in the ovaries. A dominant follicle increases in size and produces the egg. It also increases the estrogen levels in the body.
b. Ovulatory phase: This stage is characterized with the release of an egg from the dominant follicle. Rise in estrogen levels stimulates the pituitary gland to secrete LH. The LH surge causes the mature follicle to release its egg. This process is called ovulation.
c. Postovulatory phase or luteal phase: Luteal phase is the phase that follows ovulation. The empty follicle that released the egg transforms to corpus luteum and secretes a hormone called progesterone. If the egg is fertilized by the sperm, it gets implanted in the inner lining of the uterus. If not, the levels of progesterone decline, causing breakdown of lining. This again marks the beginning of bleeding.
- Nicholas Culpeper, 1660
Latest Publications and Research on OvulationThe Use of Aromatase Inhibitors for Ovulation Induction and Superovulation. - Published by PubMed
Use of Fertility Treatments in Relation to the Duration of Pregnancy Attempt Among Women Who Were Trying to Become Pregnant and Experienced a Live Birth. - Published by PubMed
Association of BMPR-1B and GDF9 genes polymorphisms and secondary protein structure changes with reproduction traits in Mehraban ewes. - Published by PubMed
Involvement of ERK1/2 signaling pathway in atrazine action on FSH-stimulated LHR and CYP19A1 expression in rat granulosa cells. - Published by PubMed
GRK-6 mediates FSH action synergistically enhanced by estrogen and the oocyte in rat granulosa cells. - Published by PubMed