Perhaps we deviate from the truth, calling our calendar age, since we do not take into account that our life began a few months earlier. The true beginning of a new life is fertilization. If it was about an animal or a plant, that would be indisputable. But when they mean a person, it’s not easy to answer the question, from what moment can you call him by this word? The task is not easy, so still not all are equally concerned with the problem of abortion: until when is it a murder?
On the one hand, from the moment of fertilization and until the birth in the womb, there is only a biological component of the future man. The environment, social factors act on it only through the maternal organism. All the diversity of the social will be influenced only after birth, and then his life will obey both biological and social laws.
On the other hand, already in the womb of the mother the future man lives his own, in many ways mysterious, life. He reacts not only to the mother's voice, but also to her mood.When does he begin to understand? Perhaps since the formation of the central nervous system. Maybe even earlier, because his cells are able to press down the changes in the chemical composition of maternal blood, and this is due to any worries of the future mother.
The beginning of the development of the embryo is interesting primarily because in the first hours, contrary to the laws of mathematics, division occurs, leading to multiplication. The cells divide, and their number increases. Not later than 30 hours after fertilization, the human embryo becomes two-cell. The next division occurs more quickly: after another 10 hours - no longer two, but four cells, after three days there are 12, and soon 16. The first cells - (blastomeres) - are larger than usual somatic cells and closely adjoin each other.
First daysthe embryo develops in the oviduct (fallopian tube) and, thanks to its contractions, the muscular wall moves to the place where it lodges for many months, to the uterus. But until the moment when such a relocation is completed successfully, both him and his mother are in danger.
If normal contact between the embryo, the wall of the oviduct and the fluid that fills the oviduct is disrupted, the embryo may either die or stop and continue its development before reaching the uterus.In the latter case, a form of ectopic pregnancy arises that is dangerous for the life of the woman, since as the embryo grows, the tube expands to the possible limit, and then it will burst. The fetus will die, bleeding into the abdominal cavity can ruin the mother. The only salvation is surgery.
When the embryo enters the uterus, it becomes like a vial and is called a blastocyst at that time. The transition to the blastocyst is accompanied by the formation of an internal mass of cells and the outer cover of a hollow vesicle. From the inner cells, the embryo will later develop, and the outer cover eventually turns into a placenta — an organ that exists in the mother’s body only during pregnancy, feeding the fetus and regulating all the relationships between it and the mother.
From the first month of existence, the skeleton of the future skeleton begins to form, it is laid in the form of a cartilage model. The skull is formed by separate flat bones, between which there are several spaces - the fontanelles. Therefore, the brain can grow without difficulty, and the volume of the skull - to increase.In the fourth week, cartilage is laid, from which the bones of the face will be formed. Each germ is different, it becomes an individual, similar or not like their parents.
Growth continues intensively, and the length of the embryo reaches 9 cm. Nails appear on the fingers, the head straightens and the neck is indicated.
In the second half of the third month, the external genitalia are formed. From the third month of development comes the fetal period, which lasts until the birth of the newborn into the world. Now it is inconvenient to call him (or her) an embryo, from now on it is about a fetus.
The length of the fetus from crown to heels is 300-350 mm, weight about 800 g. At this time, his face indicates eyebrows and eyelashes, the spike between the eyelids is torn. Increases the subcutaneous fat layer, the fluff covering the body disappears. When he turns 28 weeks old, he is capable of independent life outside the mother's body. Thanks to the achievements of modern medicine, the birth of a seven-month-old baby does not threaten his life. But at the age of seven months he is still very small: his height is 355 mm, body weight 1300 g.
All fetal organs receive mixed blood from the mother. Each portion of the fetal arterial blood (that is, blood running from its heart) loses oxygen more rapidly and rapidly than in an adult. The greatest work is performed by the right ventricle of the heart, since it is he who drives blood for a greater distance - through the lower parts of the body. The blood of the fetus is in many ways different from the blood of an adult. The main organ of blood formation from the 5th to the 20th week of intrauterine life is the liver. From the 12th week, the bone marrow function is performed by the bone marrow. The spleen begins to produce lymphocytes at the age of 14 weeks. In the bloodstream of the fetus red blood cells (erythrocytes) appear on the 8th week, and white blood cells - at 12-16. The amount of hemoglobin and blood cells in the fetus is less than that of the newborn, and by the time of birth it is gradually increasing. The fetal cardiovascular system not only transports blood. It provides respiration and nourishment to its tissues, since the blood carries both oxygen and nutrients.
The maternal organism during the entire period of pregnancy works as a complex mechanism, providing the fetus with oxygen and nutrition.The blood circulation and breathing of the mother intensively influence the formation of the unborn child.
Breathing in the sense that we imagine it (that is, using the lungs) begins only after birth. Therefore, the development of the lungs is delayed. The laying of the main structures of which the lungs and bronchi are formed, occurs in the first half of the development. By the 28th week, the fetal respiratory system reaches a level of maturation that it could function independently if preterm labor occurred.
Behindeighth monththe weight of the fetus is close to 2 kg, Length - 42 cm. The amount of fat increases, and in the ninth month the body takes on a finished look. On average, intrauterine life is 280 days (40 weeks).