Four menstrual cycles

Women's menstruation has regular cycles. According to the unique characteristics of the female body, the general cycle is 20-35 days, which is often called once a month. But in addition to this we can intuitively feel, there is also a four-cycle theory of menstruation, which was discovered based on the changes in hormones in women's bodies during each menstruation. Let's follow the editor to learn about these four cycles.

There are four cycles in each menstrual cycle of women, which include the proliferative phase, secretory phase, premenstrual phase and menstrual phase.

Proliferative phase. After the menstrual period, under the action of estrogen, the basal cells of the endometrium begin to proliferate, first repairing the wound surface at the exfoliation site, and then thickening due to continued proliferation, with the glands increasing in number, becoming wider, and gradually bending. The blood vessels also proliferate and gradually become spiral. The interstitium is dense and proliferative. This period corresponds to the stage of follicular maturation, which is around the 5th to 14th day of the menstrual cycle.

Secretory phase. It is approximately 15-23 days in the menstrual cycle, which is equivalent to the corpus luteum maturation stage after ovulation. The progesterone and estrogen secreted by the corpus luteum will cause the endometrium to continue to thicken during the proliferative phase, and the gland will further expand, bend, and secrete. The blood vessels also grow rapidly and become more tortuous. The interstitium becomes loose and edematous. At this time, the endometrium is thick and soft, containing rich nutrients, which is conducive to the implantation and development of the fertilized egg.

Premenstrual period. It is equivalent to the corpus luteum regression stage, the 24th to 28th day of the menstrual period. When the corpus luteum degenerates, the levels of progesterone and estrogen gradually decrease. This decrease in hormones will cause the intimal interstitial edema to subside and become dense, resulting in compression of blood vessels and blood stasis. Finally, local blood vessels will experience spasmodic contraction in turn, causing intimal ischemia, necrosis, and vascular rupture and bleeding.

Menstrual period. It is day 1-4 of the menstrual cycle. In the functional layer of the endometrium (the part above the basal layer, about 5-6mm thick, scattered small hematomas will cause the necrotic endometrium to peel off and be discharged with the blood, which is called menstruation. The basal layer of the endometrium then begins to proliferate and form a new endometrium. Therefore, the menstrual period is actually the end of one cycle and the beginning of the next cycle.