Ovulationrelease of a mature egg from the female ovary; the release enables the egg to be fertilized by the male sperm cells. Normally, in humansonly one egg is released at one time; occasionally, two or more erupt during the menstrual cycle.
The egg erupts from the ovary on the 14th to 16th day of the approximately day menstrual cycle. If not fertilized, the egg is passed from the reproductive tract during menstrual bleeding, which starts about two weeks after ovulation. Occasionally, cycles occur in which an egg is not released; these are called anovulatory "Amature egg." During the onset of puberty Amature egg thereafter until menopause except during pregnancythere is a cyclic development of one or more follicles each month into a mature follicle.
The covering layer of the primary follicle thickens and can be differentiated into an inner membrana…. Prior to eruption from the ovary, an egg first must grow and mature. Until stimulated to grow, the primary egg cell Amature egg through a period of dormancy that may last several years.
The egg cell is surrounded by a capsule of cells known as the follicle. The follicular wall serves as a protective casing around the egg and also provides a suitable environment for egg development.
As the follicle ripens, the cell wall thickens and a fluid is secreted to surround the egg. Once the follicle reaches the surface of the ovary, the follicular wall thins. When the follicle ruptures, the egg and fluid are released along with some torn patches of tissue.
The cells, fluid, and egg are directed into the nearby fallopian tubewhich serves as a passageway by which the egg reaches the Amature egg and as a site for fertilization of the released egg by sperm. The hormones that stimulate ovulation are produced in the pituitary gland; these are known as the follicle-stimulating hormone and luteinizing hormone. After the egg leaves the ovary, the walls of the follicle again close, and the space that was occupied by the egg begins to fill with new cells known as the corpus luteum.
The corpus luteum secretes the female hormone progesteronewhich helps to keep the uterine wall receptive to Amature egg fertilized egg.
If the egg is not fertilized, the corpus luteum stops secreting progesterone about nine days after ovulation. If the egg becomes fertilized, progesterone continues to be secreted, first by the corpus luteum and then by the placenta, until the child is born. Progesterone blocks the release of more hormones from the pituitary gland "Amature egg," so that further ovulation does not normally occur during pregnancy.
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Read More on This Topic. Learn More in these related Britannica articles: The process of ovulation has been described for all vertebrate classes. Elasmobranchs, reptiles, and birds have massively yolked eggs. As ovulation approaches, the fimbria i. Not all mammals ovulate spontaneously, however. Amature egg those that do not e.
Ovulation in women occurs at about the middle of the monthly cycle, "Amature egg" the follicular phase is succeeded by the luteal phase.
The vaginal bleeding at the end of the cycle is an indication that ovulation has not been….
The factors causing this event vary significantly, but in some such as "Amature egg" and cats, copulation itself is the main stimulus. In general, however, those mammals, particularly the large ones,…. More About Ovulation 16 references found in Britannica articles Assorted References major reference In human reproductive system: Ovulation animal reproduction In animal reproductive system: Ovaries In animal reproductive system: Role of gonads in hormone cycles birth control In contraception: Hormonal contraceptives In birth control: Methods cervical secretions In uterine cervix corpus luteum In corpus luteum fertility and infertility In infertility: Disorders of ovulation hormones In hormone: Progestins human reproduction In menstruation: Amature egg of the menstrual cycle View More.
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