Embryo development is a long, complex and interesting process. After the fusion of a tiny egg and sperm in just 9 months a new person will be born. In its development, the future child will go through several stages, and the so-called critical periods of embryo development, and will consistently be called the human embryo or embryo, then the fruit, until the moment of birth.
Stages of embryo development
The development of the human embryo begins from the moment of conception, the fusion of the spermatozoon and the ovum with the formation of a zygote, which in a few days will pass several divisions. On the fourth day it is a kind of raspberry berry in form, and consists of 58 cells. Of these cells, 5 will be needed to form the future placenta, chorion and umbilical cord, the remaining 53 - will provide further development of the fetus.
From 7th to 14th day from the moment of conception, future mothers should be especially cautious - this is the first critical period of pregnancy: the moment of implantation of the embryo into the wall of the uterus. The embryo may not be implanted for many reasons, among which:
- exposure to toxic substances;
- intensive physical activity;
- mechanical impact;
- deep vascular deposition;
- pathology of the structure and tone of the uterus.
In case of successful implantation, the embryo is fixed in the uterine wall next to the surface vessels, which will provide nutrition and development.
From 13 to 18 days the fetus is surrounded by the mucous wall of the uterus, and is in close contact with the myometrium. In this case, the envelope of the embryo forms chorionic villi, which will become the basis of the fetal egg, the chorion and the future umbilical cord. At this moment, active cell division begins, the formation of a primitive circulatory system, an amniotic fluid is formed.
From 18-21 days, when the heart of the embryo begins to beat, determine the viability of a future child on ultrasound. This is done for the purpose of diagnosing a frozen pregnancy, which sometimes occurs in the early stages of embryo development and is combined with the absence of cardiac contractions.
The first month of pregnancy is coming to an end (months and weeks in obstetrics are counted from the last menstruation, and the days from conception).
Begins 5-8 weeks, the second month of pregnancy. It is also considered critical, as all organs and systems are laid down. It is in this period that one of the main provisional organs is formed - the umbilical cord, which consists of a plexus of arteries and veins, and provides nutrition and metabolic processes of the embryo, while the placenta during pregnancy , which forms a week later, interferes with the blood of the mother and child, and hematopoietic function.
On the 20th-22nd day from the moment of conception, the formation of the rudiments of the brain and spinal cord, the intestine, then four days later the rudiments of the senses are formed-eyes, ears, nose, mouth, the tail is clearly visible. Since the second month of development, the embryo is already called the fetus. In this period, the CTE (coccygeal parietal size) of the embryo is 5-8 mm. The head is located at right angles to the trunk, limbs develop, the heart is formed.
At week 6, the CTE of the embryo increases to 15 mm, the tail bends to the trunk. Starting from 7-8 weeks - the teeth, the musculoskeletal device of the embryo are formed. Bones are translucent, very thin,
The embryo acquires a human face, the tail disappears, limbs are formed. Then follows another critical period, since all newly formed organs are very vulnerable to any toxic substances. But the fetus is no longer called an embryo. So, we described the process of embryo development in full.