THE MAIN CHARACTERISTICS OF THE STRUCTURE OF THE OVUM OF THE FEMALE BODY

Аннотация

Female germ cells are called eggs, and male germ cells are called spermatozoa. Both of them are involved in fertilization. The egg matures every month in the left or right ovary, and then leaves it to meet the male sex cell. Let's take a closer look at the structure of the egg in order to learn more about the processes that take place inside us. Key words: Egg, Ovogenesis, Gametogenesis, Cytoplasm, Nucleus, Karyoplasm Follicles with oocytes (immature eggs) are laid in a girl while still in the womb. Normally, their number is about 7 million. This number is decreasing due to diseases or bad habits of the mother, other adverse conditions, as well as natural causes. By the time of the first menstruation, 250-400 thousand cells remain. On average, a woman has 400 menstrual cycles during her reproductive age, which is the number of all mature germ cells. Several follicles grow during the menstrual cycle. Only one matures — the dominant one, the rest do not have time to mature and die. An oocyte develops in the main follicle. The mature follicle bursts, and the oocyte exits it into the fallopian tube. This means that a woman is ovulating. Conception is possible only during this period. If two eggs come out at once in one cycle, a woman can become pregnant with twins. The egg is the largest cell in the human body, it can even be viewed without a microscope, with the naked eye. It is about 20 times the size of a sperm cell. The diameter is 0.12 mm, which is comparable to a grain of sand. The oocyte has the shape of a ball. After leaving the ovary, it lives from 12 to 36 hours. After this period, it breaks down and is excreted during menstruation. Выпуск журнала №-19 Часть–2_ Февраль –2025 306 MODERN EDUCATION AND DEVELOPMENT The core In the center of the cell is the nucleus, which carries the genetic information in half a set of chromosomes. It has 23 chromosomes. The male reproductive cell contains the same amount. By uniting, they give rise to a new life. The sex of the unborn child is determined by the male sex chromosome. Cytoplasm The nucleus is surrounded by cytoplasm (ovoplasm), which contains organoids and reserve nutrients necessary for the development of the embryo at the initial stages of growth. During fertilization, the sperm gets rid of the cytoplasm. And the egg must store the substances necessary for the formation of the future embryo. The cell synthesizes some of them by itself. Organelles In addition to the nucleus, the cytoplasm contains other organelles — components of the cell that are vital for its existence. Mitochondria are called the energy stations of the cell. The main function of these organelles is the synthesis of ATP. It is a universal source of energy for all biochemical reactions in a living organism. Mitochondria contain their own DNA, which is inherited only through the maternal line. This is because male gametes lose mitochondria during fertilization. The endoplasmic reticulum consists of tubes and pockets surrounded by a membrane. This network is involved in metabolism. Protein transport and synthesis take place in it, and a supply of calcium is created. The Golgi apparatus is used to remove substances that are synthesized in the endoplasmic reticulum. It is also involved in the accumulation and sorting of substances using various enzymes. Shells The cytoplasm is surrounded by several shells at once. The yolk membrane is an internal protective layer that helps recognize spermatozoa using special protein receptors. Sperm of another biological species cannot pass through this membrane. Выпуск журнала №-19 Часть–2_ Февраль –2025 307 MODERN EDUCATION AND DEVELOPMENT The shiny shell (zona pellucida) prevents the penetration of more than one sperm. It also holds together the cells of the embryo, which at first are not yet connected to each other. Without support, they can simply fly apart. After conception, the earliest processes of cell division in the embryo take place inside the shiny shell. On days 5-6, the embryo reaches the blastocyst stage and leaves the shell. After that, it is ready for implantation into the uterine wall. The radiant crown (corona radiata) is the outer layer, which consists of special follicular cells. They are responsible for nutrition and produce the necessary hormones. The name radiant crown was given because of the appearance in the microscope: a lot of villi on the surface resemble rays. Spermatozoa that have penetrated the uterus try to destroy the surface of the egg with the help of enzymes. But only one gets inside. After this happens, the shells change, and other spermatozoa can no longer penetrate through the dense layers. In rare cases, this does happen, but a viable fetus is not formed. Features of the egg cell structure in different animal species The structure of the reproductive cells of animals depends on the method of reproduction and the conditions in which the fetus develops before its birth. In some eggs, the yolk is completely missing. Th