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A complete explanation of oogenesis starting from its latest understanding, function, process, stages, events, explanations, and diagrams.

Definition of Oogenesis

What is oogenesis? The explanation of oogenesis is the process of formation of the female egg cell. There are also those who explain that oogenesis is the process of forming egg cells from the female reproductive system. The process of oogenesis occurs in the ovaries.

In the event of oogenesis, the diploid cell oogenium or mother egg will increase and then will turn into a diploid primary oocyte. It should be understood that this process occurs in all species that reproduce sexually, including the process of immaturity of the egg cell.

Meanwhile, regarding the maturation process of the egg cell in mammals, it will go through 5 stages. The five stages are:

  • Oogenium Process
  • Primary oocyte process
  • Secondary oocyte process
  • ootid process
  • Ovum

Oogenesis Function

As for the function of oogenesis, we will explain below:

  • During meiosis, the first crossing will result in variations in
  • One oogonia will produce one egg and three polar rods
  • Polar bodies have a small amount of cytoplasm. This is useful to help in maintaining the amount of cytoplasm in the egg which is very important in the process of early embryonic development. The formation of a polar body is useful for maintaining half the number of chromosomes in the egg cell
  • Oogenesis occurs in all organisms . This supports the evidence for basic organismal relationships

Oogenesis Process

After understanding what oogenesis is and its function, the information that is no less important is about how the oogenesis process occurs. You need to know that the oogenium is a stem cell that comes from the egg in the follicular cell in the ovary.

The process in the oogenium will cause mitotic division which then gives rise to the primary oocyte and 46 chromosomes. At that time, the primary oocyte also performs mitosis which then produces 2 daughter cells of the same size. Furthermore, daughter cells that are larger in size are called secondary oocytes which are haploid.

The size of the secondary oocyte is indeed larger than the primary oocyte. The reason is because in the secondary oocyte there is a lot of cytoplasm. For small daughter cells, it is called the first polar body which will then divide again.

The secondary oocyte will leave the ovarian tube and go to the fallopian tube. When the secondary oocyte has been fertilized by a sperm cell, the mitotic division of the sperm will occur. What also happens to the first polar body will split into a second polar body so that in this process it will result in a degeneration.

However, if there is no fertilization, menstruation will quickly occur which then the cycle of oogenesis will repeat itself. When it enters the second meiotic division, the part of the secondary oocyte will change its nature to become haploid with 23 chromosomes or also called ootid.

When the ovum and nucleus are ready to fuse into one, there will be a process of releasing the egg. This process is called ovulation. In each ovulation process there is only 1 mature egg that can live within 24 hours. When the cell is not fertilized, the egg will die and will shed along with the uterine wall when it enters the beginning of menstruation.

Stages of Oogenesis

Below we will explain what the oogenium stage looks like:

1. Propagation or Proliferation

The first stage of oogenesis is called the proliferative stage. This stage occurs repeatedly. The gametogenium will initially divide into 2, 2 becomes 4, 4 becomes 8, and so on. Primordial germ cells will differentiate to become oogenium.

Furthermore, the proliferation process will take place in order to form primary oocytes and have begun to be ready to enter the growing period. For mammals, the period of proliferation occurs in the mother’s womb.

2. Growth

The second stage of oogenesis is the growth stage. This process causes the oogenium to grow bigger so that it becomes oogenium 1. This growth has a very important role because most of the substance of the egg will be used for the next development process. This differentiation is also found in the growing period.

3. Ripening

During the maturation process, there will also be two mitotic divisions. After entering the growth phase, oogenium 1 will enter the maturation stage which takes place by meiosis. At the end of meiosis 1, oogenyme 2 will be formed and at the end of meiosis 2 will be formed ootid.

4. Shape Change

The last process of oogenesis is shape change. Ootid in this phase will transform and then become gametes. For mammals, when meiosis 1 is complete in the female, 2 oocytes and one plain will form. The polocytes will be much smaller than the oocytes. This is because very little cytoplasm.

At the end of the formation of meiosis 2, one ootid and one polocite will be formed. Meanwhile, Plaincyte 1 will divide into two, although this condition is rare because it degenerates earlier. Three plain will be generated which is then absorbed by the body. In other words, the oocyte will only grow into 1 ovum in the female.

Difference between Oogenesis and Spermatogenesis

Now that you know what oogenesis is, you should now also know what spermatogenesis is . Spermatogenesis is the process of sperm formation in males. This is done by mitosis and meiosis. 

Spermatogenesis occurs in the seminiferous tubules present in the thesis. There are 4 stages that must be passed by spermatogenesis to produce 4 functional sperm cells and these four cells are considered fertile or fertile.

The stages are 1 spermatogonia, 1 primary spermatosis, 2 secondary spermatosis, 4 spermatids, and 4 spermatozoa or sperm. Meanwhile, the differences between oogenesis and spermatogenesis are as follows:

Difference Oogenesis Spermatogenesis
Definition The process of ovum formation that occurs in the female reproductive system. The method is by mitosis and meiosis The process of sperm formation in the male reproductive system. The method is by mitosis and meiosis
The place Occurs in the ovarian follicle Occurs in the seminiferous tubules in the testes
Destination Ovum formation Sperm formation
Process Does not occur continuously but has a period of rest with a fairly long period of time. Time to start menstruation until menopause Happens continuously from puberty to death
Polar body There are two polar bodies There isn’t any
Maturation place In stage 1, division occurs in the ovary and in stage 2 the division occurs outside the ovary Everything happens in the testicles
Results 1 ovum cell and 3 smooth cells or polar bodies 4 functional sperm cells (fertile/fertile)
Functional cell count 1 cell 4 cells
Division Mitosis occurs asymmetrically Mitosis is symmetrical

Those are some of the differences between oogenesis and spermatogenesis that you need to know.

Facts About Oogenis

The statements that are true regarding oogenesis are as follows:

  • Oogenesis is a process that produces a single egg cell. One primary oocyte cell produces 1 secondary oocyte and 1 polar body which will then degenerate from the ovary
  • The number of human chromosomes is 46. Because there is no division process that occurs in the oogenium, causing the number of chromosomes to be the same as that of the primary oocyte.
  • The female fetus has 7 million primary oocytes formed in the ovary. But it regresses so that there are 2 to 4 million left when the fetus is born
  • At puberty, the primary oocyte count is only 40,000
  • When the primary oocyte undergoes division in the stages of meiosis 1 and 2, the number of chromosomes remains 23 in the secondary oocyte and also one body in the ovum.