Oogenesis, the process of forming a female egg

Before the egg is cooked and ready to be fertilized, it takes a long process to go through. This process is called oogenesis. That said, oogenesis is the initial stage of a series of reproductive processes in women. In general, oogenesis is almost similar to spermatogenesis. See a full explanation of oogenicity to the process of ovulation below.

What is oogenesis?

Oogenesis is the process of forming an egg (ovum) in women, which occurs in the ovaries (ovaries). The ovaries in the embryo have about 600 thousand oogonia cells or egg stem cells. Nine weeks after the fertilization process occurs, it turns out that the fetus has also started producing eggs. When the baby girl is 5 months old, the oogonia multiply by mitosis until the number reaches more than 7 million primary oocytes. Unfortunately, this large number of primary oocytes will continue to decrease until the fetus is born.

From the initial number of more than 7 million primary oocytes, since birth primary oocytes only about 1 to 2 million remain. These egg cells will also stop growing temporarily until you enter puberty. Well, after puberty, the oogonia will actively work again following your menstrual cycle.

Of the 2 million primary oocytes, only about 400 hundred can survive until they become mature follicles. The mature follicle itself is a small pouch that has a cell wall and inside it is an egg cell. This egg cell is then released during the reproductive period. It should be understood that as you get older, the quality and quantity of the remaining ova will decrease even more. This is normal.

Oogenesis stages in the ovaries

Oogenesis begins with mitosis and meiosis. Mitosis is the process of cell division that results in two identical gametes (daughter cells). Meanwhile, meiosis is a cell division that produces four gametes, each of which has half the number of chromosomes of the parent cell.

Oogonia or egg stem cells will mature and mitotic into primary oocytes. The primary oocyte itself will later mieose into two parts to produce secondary oocytes. In contrast to the spermatogenesis process, the first meiotic division in the oogenesis process experiences an imbalanced development of the cytoplasm (cell part).

As a result, one oocyte has many cytoplasm, while the other oocyte has no cytoplasm. Oocytes that have many cytoplasm are larger than oocytes that do not have cytoplasm. Now, this smaller oocyte is what is called the first polar body.

After that, the secondary oocyte which is larger in size will undergo a second meiotic division which produces ootids. The first polar body will also split into two second polar bodies. This ootid will develop into an ovum when it meets spermatozoa, aka sperm cells. This process will later undergo degeneration or change. If after ootid degeneration does not meet sperm cells and fertilization does not occur, then the cycle of oogenesis will repeat itself and you will also experience menstruation.

Understand the female ovulation process

When the ovum and nucleus are ready to fuse together, the egg will mature and prepare to be released. This event of releasing an egg is called ovulation. This ovulation occurs every month. When a woman ovulates, only one egg will mature.

There are several stages of ovulation that you need to know, including:

1. Periovulatory. This is the stage when the lining of the egg begins to coat with mucus and prepares to move out into the uterus. On the other hand, the uterus has already prepared itself to receive eggs, so that its walls will thicken.
2. Ovulation. At this stage, there is a special enzyme that the body has to form a hole to make it easier for the egg to move through the fallopian tube, which is the tube that connects the ovaries to the uterus. The mature egg will enter the tube and pass until it reaches the uterus. In this stage, fertilization usually occurs. Fertilization (the meeting of the egg and sperm cell) occurs in the fallopian tube and can take about 24 to 48 hours.
3. Postovulatory. If the egg is fertilized by the sperm, the egg will be implanted directly into the uterine walls with assistance Luteinizing hormone (LH). However, if fertilization does not occur, the egg and the thickened uterine wall will shed. The uterine wall itself is filled with blood vessels, so that if the wall sheds blood will come out of the vagina. Well, this is when you experience menstruation, aka menstruation.

Various hormones that affect ovulation

In the process of ovulation, the reproductive hormone known as the GnRH hormone is released from the hypothalamus of the brain. This hormone is responsible for stimulating the release of two other major reproductive hormones such as Follicle Stimulating Hormone (FSH) and hormones luteinizing (LH) from the pituitary gland in the brain. FSH functions to stimulate the maturation of follicles in the ovaries. Meanwhile, LH is responsible for producing the hormones estrogen and progesterone, both of which trigger ovulation. The hormones estrogen and progesterone also cause the lining of the uterus to become thick to create a site for the development of a fertilized egg.

The egg will choose which sperm can reach it

The egg is often described as a passive "player" who just waits for the first sperm to come and enter it. In fact, studies have shown that eggs have a much bigger role than expected because they are quite picky.

Yes, the egg will actually choose which sperm can enter it. The study also shows that the eggs will trap selected sperm on their surface. As a result, sperm have no other choice. When the selected sperm enter it, the outer layer of the egg hardens to prevent other sperm from entering it. Well, at this time a sperm cell will meet an egg, otherwise known as the fertilization process.

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