Story about Menstruation, Ovulation, and Basal Body Temperature: Part 1

Fertility and Pregnancy

You may have menstruation for some years, however you may not know the mechanism of menstruation and ovulation. When you want to get pregnant, it’s better to have a knowledge about these things and basal body temperature.

In this article, we will talk about the mechanism of menstruation and ovulation as Part 1.

Understanding the mechanism of menstruation and ovulation

The female body goes through menstruation and ovulation in an approximate 28-day cycle. The normal range for the number of days in a menstrual cycle is between 25 and 38 days, with a variation of 6 days or less.

If the menstrual cycle is shortened and the menstrual period occurs within 24 days, it is called frequent menstruation. If the menstrual cycle is prolonged and occurs in more than 39 days, it is called a rare menstruation.

The number of follicles in the ovaries, which are the source of eggs, is several million when a baby is first born, and gradually decreases as the baby grows. By the time the first you have menstruation, there are only 100,000 follicles. Natural selection continues, and when there are no more atomic follicles, you will have menopause. It is estimated that 400 to 500 eggs are ovulated before menopause.

At the time you have menstruation, the pituitary gland releases follicle-stimulating hormone (FSH), which awakens about 100 atomic follicles and causes them to start growing. Although the follicles begin to grow, only one of the 100 follicles, called the master follicle, grows in size, and the others are absorbed.

Once the follicle has matured under the stimulation of FSH, the follicle membrane releases follicle hormone (E2), which is delivered to the hypothalamus. This stimulation causes the egg in the mature main follicle to break through the membrane and fly out of the ovary. This is known as ovulation.

While sperm can survive for about three to five days, the ovulated egg is only viable for about 24 hours. For this reason, people who want to get pregnant need to properly identify their ovulation date and have sexual intercourse.

Follicles that have ovulated or have not ovulated will naturally shrink in the ovary. The ovulated follicle changes to luteinizing hormone (progesterone), which causes the basal body temperature to rise and the high temperature period to continue.

If the ovulated egg is fertilized by a sperm and implants in the uterine lining, you get pregnant. However, if fertilization and implantation do not occur after ovulation, the thickened uterine lining will fall off due to the luteinizing hormone, and menstruation will begin about two weeks after ovulation.

The Meeting of Sperm and Egg

When the egg in the mature master follicle breaks the membrane and shoots out of the ovary, the oviductal vesicle, a sea anemone shaped part of the body, catches the egg and waits in the ampulla of the fallopian tube, the entrance to the fallopian tube. The hundreds of millions of sperm that are ejaculated enter the uterus and travel down the fallopian tubes to the egg.

Unlike the egg, which can only live for 24 hours, sperm can survive for an average of three to five days. With ejaculation, the race for the egg begins, and only one of the first billion sperm to reach the ampulla of the fallopian tube, where the egg is waiting, will be able to fertilize it.

The sperm emits an enzyme from its head called acrosome, which dissolves the eggshell, allowing it to penetrate the eggshell and enter the inside. At the moment of entry, a barrier called the fertilization membrane is put up around the egg, preventing other sperm from entering.

Implantation of fertilized egg and pregnant

A follicle grows in either the left or right ovary, and is ovulated by the secretion of luteinizing hormone (LH). The embryo is fertilized in the ampulla of the fallopian tube and rolls down the fallopian tube, repeatedly dividing its cells, to reach the uterus, where it implants in the softly prepared endometrium.

As the embryo rolls down the fallopian tubes, it repeatedly divides, and on the second day after fertilization, it divides into four, on the third day into eight, and on the fourth day, the division progresses even further, and the cells fuse together, making it difficult to see the dividing cells.

This day 4 embryo is called a mulberry embryo because at first glance it looks like a mulberry seed. A space is created within the mulberry embryo (formation of the blastocoel cavity). The blastocyst is the state in which that space has completely expanded. If the division proceeds smoothly, this will occur on the fifth day. After that, the blastocyst breaks free from the membrane called the zona pellucida (hatching). The embryo implants into the uterine lining.

The embryo implants on day 5-7. After implantation, the embryo produces a root-like structure called a chorion from the outside and attaches to the endometrium. There are some embryos that stop somewhere between the steps of fertilization and implantation.

If this happens, it means that implantation did not occur, and if the embryo hatches and implants firmly in the endometrium, a pregnancy will occur.


As we explained above, this is the mechanism of menstruation and ovulation. To protect your body, you need to have the right knowledge about these things. 

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