In which organs do human cells develop? Budova statevih klitin

It is important that more rich cell organisms reproduce we state way. In rich cell organisms main role In this process there are cells with a haploid set of chromosomes. gameti. With state reproduction, the release of egg cells - female state cells and spermatozoa (or sperm in naked and covered growths) - human state cells, of course daughters Organisms reproduce genetic information from both sides.
In nature, there are different types of gametes. In a number of organisms, the gametes are loose, but they vary in shape and size. And see how loose gametes can vary in size. In more highly organized species, gametes vary in size and fragility: in saviors, for example, human gametes are small and fragile, and in women they are large and indestructible. Most living plants have both male and female gametes that are indestructible.
Known from the everyday life of the article's clients. The sperm consists of a head, a neck and a long flagellum. The head has a nucleus with a set of haploid chromosomes. The sperm is located where the synthesis of ATP molecules occurs - it provides energy for the formation of the flagellum, which helps the sperm to dry out.
Combined with other cells in the body of the egg - great cells. There is a large nucleus with nuclei, a lot of cytoplasm with numerous organelles. The cytoplasm of the egg contains great quantity living substances - proteins, fats, carbohydrates. These words will ensure the nutrition of the embryo in the early stages of development. The nucleus of the egg contains a haploid set of chromosomes.

* The size of eggs in different organisms varies from several tens of micrometers to several centimeters in diameter. The number of eggs in different organisms also varies. In birds, which promise offspring, the number of eggs is small, and in fish, the number of eggs ranges from hundreds to thousands. Cod, for example, throws up to 9 million eggs. In viviparous fish that hatch about offspring, anywhere from 100 to 300 eggs are produced.

The egg cells are covered with membranes. Particularly massive membranes of eggs are found in organisms from external impregnation, for example, in most birds.
Most species of animals are separate, so their eggs are created in the female body, and spermatozoa are created in the human body. In some species, the same individual vibrates both male and female gametes. Organisms that produce both women and human tissues include simplest creatures, gutters, flatworms, parts of worms (for example, woodworms), bugs then Roslin.

The existence of human and female tissues is determined by their most important function - the development of generative reproduction. There are powerful representatives of both the growths and the creatures. The specific features of the article's clients will be reviewed in our article.

Gameti: interconnections and functions

The specialized cells that carry out this process are called gametes. Human and female cells - sperm and eggs - have a haploid, or single set of chromosomes. Such natural cells will provide the genotype to the organism, which is created when they are released. They are either diploid or sublingual. Thus, the body takes half of the genetic information from the mother, and the other part from the father.

Unrespectful on baked rice There are a lot of articles and creatures in which there are one type of one. This is where we immediately worry about the singing place of molding. Thus, in vegetative plants, sperm are deposited in the larvae of the larvae, and eggs are deposited in the ovary of the utricle. Rich creatures are toiling special bodies- plants in which the formation of state cells is possible: oocytes - in the ovaries, and spermatozoa - in the spermatozoa.

The process of molding state fabrics

The future development of state cells is determined by the course of gametogenesis – the process of their formation, which occurs in a number of stages. As a result of the multiplication phase, the primary gametes divide several times during mitosis. Which one retains a different set of chromosomes. For individuals of different statuses, this stage has its own significance. Thus, in males, the veins begin from the moment of adolescence and continue until old age. In females, the first stages of development of the fetus are formed only during intrauterine development. And until the time of state ripening, the stench will disappear from the peace.

The growth phase is like this. At this point, the primary gametes increase in size, and DNA replication begins. An important process is also the storage of living waste, even if it will be needed for further crops.

The remaining stage of gametogenesis is called the growth phase. During this process, the first stages of the cells are divided into the reduction subsection – meiosis. The result is that a number of haploid cells are created from the original diploid cells.

Spermatogenesis

As a result of the formation of human cells, spermatogenesis, many new structures are created. The stench lingers until it's gone. The human body, or rather its peculiarity, lies in certain specific devices. Zocrema, a jugella, is used for this purpose by the accumulation of human gametes. This process takes place during the prenatal phase of formation, which is characteristic of spermatogenesis.

Oogenesis

The future of female cells, as well as their formation (ovogenesis), may include a number of characteristic rice. During meiosis, the cytoplasm is distributed unevenly between the cells. Only one of them eventually becomes an egg, the beginning of future life. The other three transform into the direction of the Taurus and, as a result, collide. The biological basis for this process occurs in the reduced number of mature female cells that have matured before becoming pregnant. Only for the price of a single egg can we remove the necessary amount of living substances, which is the main mental development of the future organism. As a result, over the course of an hour, when a woman is born before having children, a total of approximately 400 individual cells will be formed. At that time, as a person, this figure amounts to hundreds of millions.

Budova human artefacts

Spermatozoa are even different cells. Their size is only a few micrometers. In nature, such dimensions are obviously compensated for by their size. The natural cells of the human body are unique.

The sperm consists of a head, neck and tail. The skin from these parts determines its functions. In the head, the permanent cell organ of eukaryotes, the nucleus, grows. It carries genetic information stored in the DNA molecule. The core itself ensures the transfer and conservation of sedimentary material. Another component of the sperm head is the acrosome. This structure is a modified Golgi complex and contains special enzymes that break down the membranes of the egg. Without it, the filling process will be impossible. The Shit has mitochondrial organelles that ensure the development of the tail. In this part of the spermatozoa there are also centrioles. These organs play an important role in the illumination of the spindle during the crushing of the fertilized egg. The tail of sperm production with microtubules, which contribute to the energy of mitochondria, ensure the growth of human cells.

Budova egg cellin

Women's cells are much larger for sperm. The diameter of ssavts should be reduced to 0.2 mm. And the axis of this indicator in lobefishes is 10 cm, and in the selenium shark - up to 23 cm. In addition, human cells and eggs of non-rukhoma are considered. The stench looms round in shape. The cytoplasm of these cells contains a large supply of living fluids in the form of a beetle. The core of DNA, which carries genetic information, contains another nucleic acid – RNA. You want to provide information about the structure of the most important proteins to your future organism. The eggs may grow unevenly in the eggs. For example, in the lancelet the vein is located in the center, and in fish it occupies almost the entire surface, destroying the nucleus and cytoplasm to one of the poles of the cell. The egg cell membrane is reliably protected by the membranes: zhovtkovaya, prozora and external. They themselves have to be broken down in the acrosomes of the sperm head to facilitate the fermentation process.

Types of sealing

The functions of these cells are related to the process of fertilization - the release of gametes. As a result of this process, the genetic material of the gametes is united in a single nucleus, and a zygote is created. Vaughn is the first tissue of a new organism.

It is important to differentiate between the external ones during this process and the first type depends on the posture of the female body. Consider the water-based environment of residence. The examples of organisms that are present in the world are representatives of the class of fish. Their females throw their eggs into the water, and the males water them with baby grass. The eggs of such creatures number in the thousands, and many of them live and grow. Most of them are aquatic creatures. And the axis for all males is characterized by internal filling, which is formed in the middle of the female body with the help of specialized males. At the same time, the quantity of eggs ready before fermentation is small.

Human and female tissues and the reproductive systems of plants are significantly different from those in animals. Therefore, the process of releasing gametes occurs differently. The human body is tall, has no tail and is up to the rump. Therefore, the zaplіdennaya is preceded by the sawing. This is the process of transferring the file from the larvae filet to the uterine silk. Here you are waiting for the help of the wind, comas or people. Having landed in this manner on the utricle, the sperm descend along the germinal tube into its expanded lower part - the ovary. The egg cell is formed there. When the gametes are released, the embryo of life is created.

Understanding about parthenogenesis

Budova statevikh klitin, zokrema women, suggests one of the unusual forms of generative reproduction. It's called parthenogenesis. Its biological essence lies in the development of an adult organism from an unfertilized egg. Such a process is avoided in life cycle Daphnia crustaceans, at any time, the state and parthenogenetic generation are being discussed. Zhinocha stateva klitina to take revenge on enough living speeches in order to give birth to a new life. Parthenogenesis is not due to the emergence of new combinations of genetic information, so the emergence of new characters is also impossible. However, parthenogenesis is more important biological significance, since it is possible for the process of statistic reproduction to proceed without the identification of an individual with a prostatic status.

Phases of the menstrual cycle

U female body During this physiological process, cyclical natural changes in the functions of the state system occur in the body. This process of the humoral system is regulated. The duration of this cycle is 21-36 days for the average period of 28. This period can be divided into three phases. In pershu (menstrual period), which lasts for approximately the first 5 days, the mucous membrane of the uterus is expelled. This is accompanied by the explosion of small blood vessels. On the 6-14th day, under the influx of the pituitary gland, a follicle is visible in which the egg cell matures. The mucous membrane of the uterus begins to swell during this period. This is the essence of the postmenstrual phase. From 15 to 28 days, the formation of adipose tissue - the belly - occurs. This is due to the role of the temporological source of internal secretion, which vibrates hormones that inhibit the maturation of follicles. In the period from 17 to 21 days, the obesity level is the highest. As this is missing, the tissue tissue collapses and the mucous membrane re-swells.

What is ovulation?

On the 14th day of the menstrual cycle, the female uterus begins to change a lot. The egg cell ruptures the follicular membrane and exits the ovary into fallopian tube. The ripening itself ends there. This process is called ovulation. This is a very important period during which the uterus becomes ready to receive the fertilized egg.

Chromosomal set of state cells

Eggs and sperm contain a single set of genetic information. For example, a human being has 23 chromosomes, and the zygote has 46. When gametes are lost, the body takes half of the genes from the mother, and the other part from the father. The same applies to articles. The middle of the chromosomes is divided into autosomes and one pair of states. Stinks appear Latin writers. In humans, women have two different chromosomes, and there are differences among humans. State clients want to take revenge on one of them. Thus, in order to become a future child, it will remain in the human body and in the form of chromosomes that carry sperm.

Functions of state cells

A woman's body, like a man's, is interconnected with the functions that die. As part of the reproductive system, it performs the function of generative reproduction. Instead of a stateless one, in which the integrity of the genetic information of the organism is preserved, the breeding state will ensure the creation of new characters. This is a necessary mental adaptation, and therefore, of all the creation of living organisms.

Gamete: germ cell (sperm or egg cell), which contains a haploid set of chromosomes, so it contains one copy of skin chromosomes.

With the state method of reproduction, the offspring have two fathers. The skin from the father is vibrating the tissues. Cells, or gametes, contain half or a haploid set of chromosomes and result in meiosis. Thus, a gamete (from the Greek gamete - squad, gametes - man) is a mature reproductive cell that contains a haploid set of chromosomes and is created when it is united with a similar cell of the prostatus state to create a zygote, at which number The chromosomes remain diploid. In the diploid set, the skin chromosome is paired with a homologous chromosome. One of the homologous chromosomes is like the father, the other is like the mother. A female gamete is called an egg, a human gamete is called a sperm. The process of creation of gametes is called gametogenesis.

In embryos of all spinal columns early stage The development of song cells is strengthened as the predecessors of future gametes. Such primary cells migrate from the gonads that develop (ovaries in females, ovaries in males), and after the period of mitotic reproduction they undergo meiosis and differentiate into mature gametes. In state cells, before meiosis, accessory genes are activated that regulate the pairing of homologous chromosomes, recombination and subsections of recombined homologous chromosomes in anaphase of the first subsection.

Egg cells develop from the primary cells, which at an early stage of development of the body migrate to the ovary and transform into ogonium there. After the period of mitotic reproduction, oogoniums become first-order oocytes, which, having entered the first stage of meiosis, are locked in prophase I for an hour, which remains in cycles or cycles in the type of organism. During this period, the oocyte grows and accumulates ribosomes, mRNA, and proteins, often resulting in other cells, including additional cells that are about to leave. The fused socket (dreary eggs) to lay the wid of half -peptid hormones (Gonadotropiniv), yaki, sculpture on the dubbing of the skin of the oocyt, sponuccum of the subsidiary of the small part of the oocytin. These oocytes complete the first stage of meiosis, producing a small polar body and a large oocyte of another order, which transforms into metaphase of the other stage of meiosis. In many species, the oocyte is arrested at this stage until the sealing initiates the completion of meiosis and the development of the embryo.

Sperm is called a small and compact cell, as in high level is specialized for the function of introducing its DNA to the egg. While in rich organisms the entire pool of oocytes is established even at the early stage of female development, in males, after reaching maturity, more and more cells enter into meiosis, and the skin spermatocyte first This order gives rise to four mature sperm. Sperm differentiation occurs after meiosis, if the nuclei are haploid. However, during the mitotic division of mature spermatogonia and spermatocytes, cytokinesis is not brought to an end; parts of one spermatogonia develop in one

One of the first stages of the process between cells in the body, which practically avoided the faults of the rich cell organisms themselves, was the stage of somatic and cellular conditions. Since then, the evolutionary, cell-rich organisms have been divided into two groups: those that create cellular tissues from somatic needs in the world, and those that are already embryos in the early stages This development is visible and for the moment “preserves” the surrounding population of cells – predecessors of the state . klitin.

© jessy731/Flickr

In humans, for example, the first stages of the cells develop in the fifth stage of embryonic development at the ovary sac. At this time, the rudiments of the gonads - ovaries and spermatozoa - have not yet formed, but if they are formed, the first elements of the cells migrate here and there and are lost. A similar pattern of primary cells is seen in most animals that are more complex than intestinal emptying ones. In some species of comas, the proportion of state cells appears extremely early: already in unfertilized eggs In one of the poles there are protein granules and parts of the cytoplasm with granules after crushing are created by the primary cells.

All plants and primitive creatures that previously lived under the influence of the evolutionary plant (sponges, ctenophores, jellyfish, flat tanks etc.) there are no specific purposes for the article. The stench originates from somatic tissues and can only live in somatic tissues until the organism begins to reproduce.

Until now there was no such theory, which would have successfully explained that early “preservation” of state cells was needed.

One of the explanations given by turbot is about saving genetic material. Indeed, with the skin division of the cell, a sub-warning of chromosomes occurs and, when copied, abrasions occur. The number of such cuts per copy is small, but the more copies there are, the more cuts there are. In metabolically active cells, through oxide-based reactions, necessary for the generation of energy (ATP synthesis), it is more aggressive dovkilla, Higher concentration of free radicals. As they are infused, new mutations may appear on the DNA, even though copying is not currently taking place.

Between Hayflick and telomere

Inaccuracies during replication and active metabolism are associated with the accumulation of mutations in the cell genome. The accumulation of mutations can lead to malignant degeneration of the cell, and then the death of not just one cell, but the entire organism. To protect against such selfish behavior, a basic boundary is applied to the somatic cells of rich cell organisms - the Hayflick interval - the maximum number of sections that can be formed on the cell. For human cells, the Hayflick distance is as high as 52. Technically, the Hayflick gap is due to telomeres, the sequences at the ends of chromosomes. When the chromosomes are subwarned, the polymerase, through its spacious structure, cannot begin work from the end of the chromosome, and the transcript immediately becomes shorter and shorter. As long as the telomere is lost, the cell is alive. As soon as the telomeres end, the genome becomes unstable and cells become unstable. Side effect Such replicative connections may be old for the organism. On the whole, Hayflick's line of art does not expand - it is potentially immortal and passes from generation to generation, shuffling genetic material. This kind of immortality is achieved through the activity of telomerase, the enzyme that sustains telomeres. It is true that at this rate the price of the negative mutation that has occurred increases. Since the cells from the mutation are involved in the process of spreading, the mutation is reduced by all cells in the new organism. Such an organism may be less stable or may become sick or die.

Prote, against conservation of the state line for the sake of Have a great relationship to nuclear DNA is a serious argument. Vіn have the one who, from whose view, is preserved more than a woman’s body. Human cells are already actively dividing and undergoing about 30 divisions in humans at the time of maturation and about 400 (!) - Up to 30 years. From this point of view, the human anterior cells act like somatic tissue - there is a particularly strong similarity with the cystic cerebrospinal fluid, in which a small number of stovburian cells are constantly dividing intensively to protect the organ Measurement of short-lived blood elements. Through such an intensive division of the progenitor spermatozoa, the DNA of the offspring may have already reached a large number of mutations similar to the father’s.

© Darryl Leja/National Human Genome Research Institute

To assume another, plausible reason for the appearance of conservation of cells in the state line is the equal role of the sperm and egg during fertilization. At the moment of fertilization of the sperm into the egg, the nucleus is lost, the cytoplasm and all organs are given to the future embryo from the egg. Okrema, all the mitochondria of the new organism are reduced by the mother. Mitochondria provide energy to the cell. Being historically bacteria that developed a symbiosis with eukaryotes, they store surplus Vlasny genome. The mitochondrial genome is more similar to the bacterial genome than the eukaryotic one. It is represented by one circular chromosome and does not undergo homologous recombination. Mitochondria are divided like primary bacteria, whereby the two daughter mitochondria remain identical up to the chromosome mutation that has just appeared. This means that if there is a mutation that has occurred in the mitochondrial DNA, it can be eliminated, only if the mitochondria are not lost to the state line of the next generation (small Obviously, because the mitochondria were unable to multiply, or because the body cannot be deprived of offspring at all. From this it turns out that the price of such a mutation of a substance.

However, besides the unfortunate mutations there is another problem. Without them, evolution would have been impossible, because first of all, everyone would have been the same, and otherwise, they would not have survived the drastic change of minds. Therefore, the number of mutations may vary: neither too great nor too small.

The assumption that isolation of cells of the state line is required for proper preservation of egg cell mitochondria has been around for a long time. Ale, it became clear, to conduct an experiment on the scale of evolution from the ancestral ancestor of all eukaryotes until you want some hrobaks absolutely impossible. Tom Nick Lane of University College London and his colleagues used a mathematical model to confirm this hypothesis. The robot's work has been published electronically scientific journal PLOS Biology.

U different hour In various experiments, the frequency of new mutations in mitochondrial DNA was assessed different species. It turned out that the amount is low for tall and primitive creatures, but there is a lot more for complex creatures, including the Saviors. The reasons for this are completely clear. It was planned that the transition to a loose way of life and watering, hanging the tough ones in order to ensure energy-saving cells, and to remove effective mitochondria, the frequency of culprit mutations was increased.

There is, however, a clear correlation between the frequency of culprit mutations in mitochondrial DNA and the conservation of female state cells. The authors of the work developed a mathematical model that evaluates the adaptability of the body depending on the frequency of mutations in mitochondrial DNA. It turned out that due to the high frequency, for example, in humans, without conservation of female state cells, mutations in mitochondria accumulated even rapidly.

Zagalom, this mathematical model clearly shows the nutrition, it was finally necessary to preserve the tissues of the state line. Ale, being a mathematical model, there is that little bit that only accumulates on the already removed current moment experimental data on the frequency of mutations during the replication of mitochondrial DNA in various species. If tomorrow in new experiments we will find a tree with a high frequency of mutations or a backbone with a low one, the theory will have to be reviewed or completely supplemented.

The authors also admit that their theory explains the still unknown phenomenon of follicular atresia. During the embryonic development of the human female body (similarly to that in many other creatures), approximately 6 million oocytes (progenitor oocytes) are created. Then over 90% of them die instantly, and about 500 thousand of them die before puberty. It is important to realize what is being released through the low acidity of cells. The authors of the study assumed that this phenomenon had emerged in order to correct the small variability in mitochondrial DNA that had arisen through the conservation of cell lineages. Following these assumptions, the cells will be divided several times in order to eliminate more different variants of mitochondrial DNA, and then some of them will be eliminated so that cells with the most dissimilar variants will be left alive.

This variability is very important; it itself is material for evolution and the selection of the most viable options. Zmagannya between different options oocytes begin even earlier. During the skin cycle in humans, a number of follicles begin to mature, but one of them swells forward, and the others, as a rule, die (this itself explains the low frequency of the birth of fraternal twins in humans). It is possible that the greatest advantage of this invention is the efficiency of mitochondrial functioning.

The authors of the work are entirely aware of the fact that their assumption is nothing more than a hypothesis, which cannot be confirmed by experimental data, but may still be unfounded. Protean incomprehensibly explains the phenomenon that has previously been attempted to be explained from the cob - the preservation of the cells of the state line (most importantly, in the female body). In addition, this hypothesis usefully explains other previously unexplained findings - for example, the excessive proliferation and massive loss of progenitor eggs.

The state of reproduction occurs among representatives of all types of vegetable and vegetable species. It is associated with the creation of special state cells: women - eggs and humans - sperm.

State species (gametes) are characterized by a non-single (haploid) number of chromosomes (div.). In addition, they arise from the relationship between the cytoplasm and the nucleus (aligned with somatic cells).

Human body cells (spermatozoa)

Human cells - spermatozoa - are even more fragile and crumbling. Typical spermatozoa are formed from a head, neck and tail.

Head The core consists entirely of a nucleus, covered with a thin ball of cytoplasm. The front plot is fenced off and covered with a carpet.

Shiyka It is sound, it contains the centriole (the storage part of the cell center) and mitochondria.

Tail Spermatozoa are composed of very thin fibers covered with a cytoplasmic cylinder: the vein and organoid organ.

The full length of the spermatozoon, including the head, neck and tail, is 50-60 µm in sperm and people. It is typical that spermatozoa mature in large numbers (hundreds of millions of sperm mature throughout their lives).

Budova woman's tissue (ovum)

Women's cells (ovules) are intact and, as a rule, have larger spermatozoa. The stench will cause the kulyastu to form and the different husks of the shells. In savages, the egg cell size is still small and reaches 100-200 µm in diameter. In other spinal organisms (fish, amphibians, reptiles, birds) large egg cells. The cytoplasm has a stench that can be felt even by many living creatures.

In birds, for example, the egg is that part of the egg that is called the egg. The diameter of the chicken egg is 3-3.5 cm, and in such great birds as ostriches it is 10-11 cm. These egg cells are covered with a number of membranes of a collapsible shell (ball of the white, sub- and scallop membranes, etc.), which ensures the normal development of the embryo.

The number of eggs that are fertilized is significantly less than the number of sperm. For example, a woman matures about 400 eggs throughout her life.

The future of human and female species of plants has been described.

Development of eggs and sperm

The ripening and development of state cells is called gametogenesis. In animals and humans, they develop in ovaries: eggs develop in ovaries, and spermatozoa develop in testicles.

Stages of development

The process of development of human sperm cells (spermatogenesis) and female sperm cells (ovogenesis) may result in similar figures. Both in the ovary and in the eggs there are three different stages:

• Reproduction stages;
• stages of growth;
• stages of maturation of state cells

on first stage Spermatogonia and ovonia (cells - the progenitors of sperm and eggs) multiply in droves and their number increases.

In humans, the mitotic section of spermatogonia begins during the period of maturation and continues for dozens of years. For wives, the fire begins only during the embryonic period of their life and will end even before marriage. In animals, these cells are divided during the terms and periods of reproduction.

U other stage spermatogonia and ovonia cease to multiply, begin to grow and increase in size, transforming into the primary spermatocytes and oocytes. It is especially important to increase the size of oocytes. For example, toads have linear dimensions and the oocyte is more than 2 thousand. once, nizh in ogonnі. This means that they accumulate lifelong speeches necessary for the development of the embryo.

The most important changes are being made with the upcoming article clients on third stage ripened Here the essential differences between spermatozoa and oogenesis are revealed. In this zone, the primary oocytes undergo two stages of meiosis. With the first meiotic division, the great secondary oocyte and the small cell, the primary oocyte, are created (first polar, or to the right, body).

In another meiotic division, the secondary oocyte divides into a large immature oocyte and a smaller secondary oocyte (another polar body). The primary polocyte can also divide into two more polocytes.

Thus, as a result of two meiotic divisions, one primary oocyte produces 4 cells with a haploid set of chromosomes - an immature cell (which transforms into a mature egg) and three cells that are about to die.

During spermatogenesis, the primary spermatocyte in the maturation zone also divides through meiosis. However, there are 4 new haploid spermatids. Next, a series of folding changes (changes in shape, development of the tail) are transformed on the mature sperm.

Zaplіdnennya

Zaplіdnennya- this is the process of fusion of sperm nuclei and egg cell and renewal of the diploid set of chromosomes. The egg cell is sealed and becomes a zygote. The zygote is formed when the sperm penetrates into the egg.

This process occurs differently in different organisms. In spermatozoa, penetration of the sperm into the egg is accompanied by breakdown of the membrane with the help of various enzymes that are present in the sperm. In many comas, the oocytes pierce the thick membrane and the sperm penetrates through small openings. In some aquatic organisms, on the surface of the egg, a small hump is created at the point of contact with the sperm, which is then drawn in between the sperm.

When the cytoplasm of the egg cell penetrates only the head of the spermatozoon with the mitochondria and the centriole, and the tail is lost. The shell of the head breaks down, the core begins to swell until it reaches the size of the egg nucleus. Then the offended nuclei get closer and, together, get angry.

Sometimes a small number of spermatozoa penetrate the egg, but only one of them is released from the nucleus. In the zygote, all chromosomes become pairs: in each pair of homologous chromosomes, one chromosome belongs to the egg cell, the other belongs to the sperm. This is of great importance for evolution. The organism that develops from zygote has a great range of combinative flexibility, and therefore a wider ability to adapt to the minds of a more middle-class mind.

Typical for kvitkovyh roslins.