Fertilization is a process thatis the fusion of male and female sex cells. It would seem that nothing is so complicated in it, but in reality the situation is somewhat different. Fertilization is not a one-stage process.
What are the characteristics of the sex cells, and why are they needed?
Female gametes are called egg cells. They are large enough to compare with other cells. At the same time, strangely enough, but by the amount of genetic material, such a cell loses twice as much as usual autosomes (not sex cells). This is due to the fact that the ovules are formed due to meiosis, and not mitosis, like the rest. Such a mechanism for the creation of gametes is simply necessary, since this allows a normal diploid (double) set of chromosomes to merge with male and female sex cells. So the future baby receives signs both from the father, and from mother.
How do "meet" the egg and sperm?
Male and female sex cells are small enough. Most often they find each other in the ampullar part of the fallopian tubes. Business is not as simple as it might seem at first glance. This is due to the fact that, in comparison with the lumen of the fallopian tubes, the dimensions of the sex cells are negligible. It is for this reason that a mechanism is needed for the ovum and sperm to be able to find each other. It is called "chemotaxis" (directed movement). Thanks to him, the fertilization of the cell by the male gamete is relatively simple.
What happens after fertilization?
After the sperm and the eggthey merge into a zygote, embryo development begins. In the future, the zygote gradually moves through the fallopian tubes and after 7-10 days it enters the uterine cavity. There, the embryo is introduced into its wall and begins to receive nutrition from the mother's body. Over the next few weeks, it remains unformed and increases in size quite slowly. Gradually, the body is divided into 3 main tissues - mesoderm, ectoderm and endoderm. Each of them participates in the formation of various systems of embryo organs. During this period, it is very important not to harm the developing organism in any way, as this can lead to significant defects in its formation. So fertilization is a very difficult process, but everything that happens in the future has even greater significance.
When is the conception of a child difficult?
Several conditions must be met to ensure thatsuccessful fertilization has occurred. It is very important to know. Today, one of the most common problems is obstruction of the fallopian tubes. With this pathology, fertilization becomes impossible. This is due to the fact that the spermatozoon is simply unable to reach the ovum.
In recent decades, there has been a declinethe concentration of germ cells in sperm and a decrease in its total volume. All this leads to the fact that spermatozoa are simply too small to reach the ampullar part of the fallopian tubes.</ p>