Which comes first, menstruation or ovulation?

Female friends always don’t understand whether they menstruate first or ovulate first, but in fact these two situations are completely separate. Generally, ovulation comes first, so you cannot have sex during this period. If you have sex, the chance of conception will increase. You must also pay attention to regulating your body and not let any problems occur in your physical condition.

Ovulation is the release of a mature egg from the ovary. After a woman is born, there are about 300,000 to 600,000 follicles in both ovaries, but in a person's lifetime, only about 400 follicles can mature, and the rest degenerate. The process in which the mature follicle ruptures and the egg is discharged from the ovary into the abdominal cavity is called ovulation. Ovulation usually occurs about 14 days before your period. For example, if your period starts on October 28, then October 14 is the ovulation period.

An egg is a female's reproductive cell, produced one per month by one ovary. The egg must mature before it can be released from the ovary. The egg matures in a fluid-filled vesicle, and the image of a jellyfish is very appropriate to describe the egg. A woman releases about 400 eggs in her lifetime, and at most 500 eggs. The average survival time of an egg is 12 to 24 hours. There are also reports that an egg can survive for 36 hours, which should be a relatively "strong" egg. The diameter of a mature egg can be 1 mm. As the largest cell in the human body, the egg plays a role in human reproduction.

Before ovulation, the primary oocyte completes the first meiotic division to produce the secondary oocyte and the first polar body. The secondary oocyte then enters the second meiotic division and arrests at metaphase. Generally, ovulation occurs once every 28 to 35 days, with the two ovaries taking turns ovulating. Normal ovulation occurs on the 14th day before the next menstruation.

(1) Decreased follicle wall tension

Before ovulation, the pituitary gland secretes more LH, which can promote the secretion of progesterone. The latter prompts the ovaries to synthesize a variety of enzymes, which denature the proteoglycans that act as adhesion between the collagen fibers in the top tissue of the mature follicle, thereby reducing the tension of the follicle wall.

(2) Enzyme dissolves the follicle wall

It has been proven that there are proteolytic enzymes, amylase, collagenase, hyaluronidase, etc. in follicular fluid. Therefore, it is believed that ovulation is caused by the above enzymes dissolving and rupturing the follicle wall, leading to ovulation.

(3) Related to prostaglandins

LH can promote the synthesis of prostaglandins by granulosa cells, and the PG content in mature follicles increases progressively as ovulation approaches. PG2α can promote the contraction of smooth muscle fibers in the interstitial tissue surrounding the follicle, causing the follicle to rupture and ovulate.