Ovogenesis is the process of egg formation. Spermatogenesis and oogenesis

Reproduction or reproduction of offspring to light is one of the most important destinations of all living beings of our planet. Genetic material is transmitted from parents to offspring, which allows a fairly long time not to interrupt their kind. Today we will talk in more detail about the continuation of the human race. Consider such concepts as spermatogenesis and oogenesis. How does the process of reproduction begin? Of course, with the penetration of the male cell into the female. Where do they come from? We are interested in the process of gametogenesis. Ovogenesis is a sequential process of formation of the female sex cell. Spermatogenesis is the formation of the male sexual cell. Today we will analyze what the similarity is, and what is the difference between these processes.

Egg

We have already mentioned that oogenesis is the process of reproduction of the female reproductive cell, which has the name "egg cell". We offer a little talk about why it is needed and what function it performs. Let us briefly consider the structure of the egg.

As mentioned earlier, an ovum is a sex cell with a rounded shape. It necessarily contains all the necessary nutrients, because its main function is to ensure the development of the body from the moment of fertilization. Like any other cell, the egg in the center itself contains a nucleus. Around the nucleus with a haploid set of chromosomes is the cytoplasm. The egg has an upper protective layer - a radiant crown. This name was given to this shell because it consists of a large number of small villi.

Near the nucleus, as a result of meiosis, another small body is formed, this formation is a cell of very tiny sizes. In all, the newborn girl in stock has about a million egg cells. But over time, many of them die. Until the time of puberty, there are only about 300,000, and about 400 of them are ovulating. Where do all the others go? They just die, and before they have time to ripen.

We suggest discussing the process itself called "oogenesis". This is the maturation of those same female sex cells. Let's start right now.

Ovogenesis

Ovogenesis is the formation of female sex cells. It is immediately necessary to clarify that in mammals it begins before birth, that is, in utero. Before we list and characterize all the stages of oogenesis, let us single out the main purpose of this process. So, the functions:

• The haploid set of chromosomes should form in the nucleus of the oocyte;
• Satisfaction of the zygote in the presence of nutrients.

We can immediately note that the process of ovogenesis is not very different from spermatogenesis, you will notice this further.

So, the stages of ovogenesis are distinguished by the following:

• Reproduction;
• growth;
• maturation.

The very first stage is still in the womb. The girl already has a large number of primary sex cells, which at this stage can be called: rudiments or embryos. These future eggs are very actively divide, so there is an accumulation of ovonia. They accumulate in the cortical layer. It is the ovony that accumulates all the necessary nutrients, namely:

• protein;
• Fats;
• glucose.

What is the difference between ovony and embryonic cells? They are larger in size. Their similarity is that the genetic makeup is the same.

If we briefly consider the second phase, we will see that it occurs also before the birth of the girl. Now oocytes are formed by first-order oocytes. The size at division considerably decreases, but the oocytes quickly gain their mass. Further, future eggs are waiting for a long conservation in the form of prophase oocytes. Now there are about two million of them, and only about 400 oocytes will develop further.

The last stage occurs after a large amount of time (about 11-12 years, and sometimes more). At this phase, one of the conserved oocytes suddenly begins to develop further. The result will be the arrival of monthly.

Sperm

We learned that in the oogenesis there is a female sexual cell called the egg. Now we pass to spermatogenesis and the male sexual cell. So, to continue the human race, you need a pair of eggs that can fertilize it. Spermatozoon - this is the necessary half.

In the male body of spermatozoa, there may be many millions, in contrast to the ovules in the female body. They consist of:

• From the head;
• Neck;
• The middle part;
• The filiform tail.

When the sperm reached the egg, the tail, necessary for movement, disappears. Further, the female germ cell passes only the head of the spermatozoon into itself, as it carries genetic material. As you know, the shell of the egg is quite strong, so on the head of the sperm there is an acrosome. It contains a special substance that can dissolve the shell. The size of one male germ cell is only 0.05 millimeters, so in order to see it, you need a powerful microscope.

Spermatogenesis

Spermatogenesis and oogenesis are fairly similar processes. In the first, the following stages are distinguished:

• Reproduction;
• growth;
• maturation;
• Formation.

At the stage of reproduction, more than a thousand spermatogonia are formed by dividing each about ten times. During the division, they absorb nutrients.

In the process of growth, they greatly increase in size. It is at the stage of growth that the transformation of spermatogonia into spermatocytes of the first order takes place.

At the stage of maturation, there are 2 divisions:

• Meiosis (as a result we have spermatocytes of the second order);
• Mitosis (spermatids are formed).

During the formation of spermatids enter into a connection with the processes of the cell, and sperm are formed. When they finish their formation, they gain mobility.

Similarities

It is immediately worth noting the first similarity of oogenesis and spermatogenesis - both processes are needed for the formation, maturation and growth of sex cells, male or female. Although there are many similarities in the processes, it is possible to identify some differences.

Another common feature is the almost identical stages of the process (spermatogenesis has one more stage). General stages:

• Reproduction;
• growth;
• maturation.

We examined the details of these steps in detail above. Let's proceed to the differences.

Differences

Let's start with the fact that in ovogenesis and spermatogenesis we have different results, oogenesis corresponds to such a result as the formation of the female sex cell, and spermatogenesis is male. As you have already noticed, in the process of formation of spermatozoa at one stage more than in the formation of the egg. The first pass also the stage of formation, while oogenesis does not need this stage at this stage.

The process of oogenesis begins in girls in the womb, and spermatogenesis begins in boys who have reached the age of 12. This is another difference.

The last difference is in more male sex cells than in female sex cells. This can be explained as follows: only one sperm of about 200 million gets to the oocyte.