What is the luteal phase? Do you know?

The luteal phase is a special stage for women. Do you know what the luteal phase is? In fact, the luteal phase refers to the period from ovulation to the day before menstruation. The luteal phase usually lasts 14 days and ends on the first day after menstruation. Moreover, a woman's body temperature during the luteal phase will be higher than normal, but no other obvious symptoms will occur.

What is the Luteal Phase?

The luteal phase is the period from ovulation to the day before menstruation. The luteal phase is relatively constant in length, averaging 14 days in non-pregnant women and ending on the first day of menstruation.

After a woman ovulates, under the action of luteinizing hormone, the ovarian cells further divide, and the cytoplasm will have yellow pigment particles and fat droplets, which appear yellow to the naked eye, so we call this new endocrine gland the corpus luteum. The development and outcome of the corpus luteum depends on whether the egg released by the follicle is fertilized. If not, it will last for about 14 days and then degenerate, which is then manifested as menstruation in women. If the egg has been fertilized, the corpus luteum will last until the end of the third month of pregnancy before degenerating.

Formation and degeneration of the corpus luteum:

1. After ovulation, the follicular fluid flows out, the pressure in the follicular cavity drops, the follicular wall collapses, and many wrinkles are formed. The granulosa cells and endometrial cells of the follicular wall invade inward and are surrounded by the follicular outer membrane of connective tissue to form a corpus luteum.

2. Under the action of the ovulation peak of LH (luteinizing hormone), the granulosa cells and theca cells of the follicle are further luteinized to form granulosa-lutein cells and theca-lutein cells respectively. Both types of corpus luteum cells contain carotene, and the amount of this pigment determines the depth of the color of the corpus luteum.

3. 7-8 days after ovulation (equivalent to around the 22nd day of the menstrual cycle), the volume and function of the corpus luteum reach its peak, with a diameter of 1-2 cm and a yellow appearance. The establishment of normal corpus luteum function requires ideal preovulatory follicle development, FSH (follicle stimulating hormone) stimulation and a certain level of continuous LH (luteinizing hormone) maintenance.

4. If the discharged egg is fertilized, the corpus luteum will enlarge under the action of hCG (human chorionic gonadotropin) secreted by the embryonic trophoblast cells, and transform into a corpus luteum of pregnancy, which will only degenerate at the end of the third month of pregnancy. The placenta then forms and secretes steroid hormones to maintain pregnancy.

5. If the egg is not fertilized, the corpus luteum begins to degenerate 9-10 days after ovulation, and its function is limited to 14 days. When the corpus luteum degenerates, the luteal cells gradually shrink and become smaller, and the surrounding connective tissue and fibroblasts invade the corpus luteum and are gradually replaced by connective tissue. The tissue becomes fibrotic and white in appearance, which is called the corpus albicans. After the corpus luteum declines, menstruation occurs, new follicles develop in the ovaries, and a new menstrual cycle begins.