Our bodies are well made but incredibly sensitive machines. Read the wondrous mechanism of the endometrial cycle. It will give you a new found respect for your amazing body.
The endometrium is the tissue lining the inner cavity of the uterus (or womb) which is the hollow organ about the size and shape of a pear. The upper part of the uterus is called the corpus; the lower, narrower part of the uterus is called the cervix. The cervix is the opening between the uterus and the vagina. The outer layer of the uterus is called the myometrium. The myometrium is thick and composed of strong muscles. These muscles contract during labor to push out the baby.
Our bodies go through three stages during endometrial cycle.
1- Estrogen phase, before ovulation:
This phase begins on day one of your cycle, and lasts until about day 14. It’s where the endometrium grows to form a lush lining inside your uterus.
At the beginning of each monthly cycle, most of the endometrium has been shed by menstruation. After menstruation, only a thin layer of endometrial tissue remains, and the only cells that are left are those located in the remaining deeper portions of the glands and crypts of the endometrium.Under the influence of estrogen, secreted in increasing quantities by the ovary during the first part of the monthly ovarian cycle, the tissue cells and the epithelial cells proliferate rapidly. The endometrial surface is healed within 4 to 7 days after the beginning of menstruation.
Then, during the next week and a half—that is, before ovulation occurs—the endometrium increases greatly in thickness, owing to increasing numbers of tissue cells and to progressive growth of the endometrial glands and new blood vessels into the endometrium. At the time of ovulation, the endometrium is 3 to 5 millimeters thick.
The endometrial glands, especially those of the cervical region, secrete a thin, stringy mucus. The mucus strings actually align themselves along the length of the cervical canal, forming channels that help guide sperm in the proper direction from the vagina into the uterus.
2- Progestational phase, after ovulation:
This is when your body secretes the hormones estrogen and progesterone. The two work together to prepare the lining of the uterus for implantation, if it should occur. This phase lasts about 12 days
During most of the latter half of the monthly cycle, after ovulation has occurred, progesterone and estrogen together are secreted in large quantities by the corpus luteum ( a temporary endocrine structure). The estrogen causes slight additional cellular proliferation in the endometrium during this phase of the cycle, whereas progesterone causes marked swelling and secretory development of the endometrium. The glands increase in tortuosity; an excess of secretory substances accumulates in the glandular epithelial cells. Also, the cytoplasm of the tissue cells increases; lipid and glycogen deposits increase greatly in the cells; and the blood supply to the endometrium further increases in proportion to the developing secretory activity, with the blood vessels becoming highly tortuous. At the peak of the secretory phase, about 1 week after ovulation, the endometrium has a thickness of 5 to 6 millimeters.
The whole purpose of all these endometrial changes is to produce a highly secretory endometrium that contains large amounts of stored nutrients to provide appropriate conditions for fertilization during the latter half of the monthly cycle. From the time a fertilized ovum enters the uterine cavity from the fallopian tube (which occurs 3 to 4 days after ovulation) until the time the ovum implants (7 to 9 days after ovulation), the uterine secretions, called “uterine milk,” provide nutrition for the early dividing ovum. Then, once the ovum implants in the endometrium, the trophoblastic cells on the surface of the implanting ovum (in the blastocyst stage) begin to digest the endometrium and absorb the endometrial stored substances, thus making great quantities of nutrients available to the early implanting embryo.
If you don’t conceive this month, levels of estrogen and progesterone start to decline and the endometrial lining begins to shed, which typically lasts 3 to 5 days.
Menstruation is caused by the reduction of estrogen and progesterone, especially progesterone, at the end of the monthly ovarian cycle.The first effect is decreased stimulation of the endometrial cells by these two hormones, followed rapidly by shrinking of the endometrium itself to about 65 percent of its previous thickness. Then, during the 24 hours preceding the onset of menstruation, the tortuous blood vessels leading to the mucosal layers of the endometrium become constricted, presumably because of some effect of the shrinkage, such as release of a vasoconstrictor material—possibly one of the vasoconstrictor types of prostaglandins that are present in abundance at this time.
The vasospasm, the decrease in nutrients to the endometrium, and the loss of hormonal stimulation initiate necrosis in the endometrium, especially of the blood vessels. As a result, blood at first seeps into the vascular layer of the endometrium, and the hemor-rhagic areas grow rapidly over a period of 24 to 36 hours. Gradually, the necrotic outer layers of the endometrium separate from the uterus at the sites of the hemorrhages until, about 48 hours after the onset of menstruation, all the superficial layers of the endometrium have desquamated. The mass of desquamated tissue and blood in the uterine cavity, plus contractile effects of prostaglandins or other substances in the decaying desquamate, all acting together, initiate uterine contractions that expel the uterine contents.
During normal menstruation, approximately 40 milliliters of blood and an additional 35 milliliters of serous fluid are lost. The menstrual fluid is normally non-clotting because a fibrinolysin is released along with the necrotic endometrial material. If excessive bleeding occurs from the uterine surface, the quantity of fibrinolysin may not be sufficient to prevent clotting.The presence of clots during menstruation is often clinical evidence of uterine pathology.
Within 4 to 7 days after menstruation starts, the loss of blood ceases because, by this time, the endometrium has become re-epithelialized.
Leukorrhea During Menstruation. During menstruation, tremendous numbers of leukocytes are released along with the necrotic material and blood. It is probable that some substance liberated by the endometrial necrosis causes this outflow of leukocytes. As a result of these leukocytes and possibly other factors, the uterus is highly resistant to infection during menstruation, even though the endometrial surfaces are denuded. This is of extreme protective value.
Then the whole thing starts all over again.
Information Source: Braincart.com. TheBump.com
Photo Credit: Sam Manns