Fertilization is a process that is the fusion of male and female sex cells. It would seem that there is nothing so complicated in it, but in reality the situation is somewhat different. Fertilization is not a one-time process.
What are the features of germ cells, and why are they needed?
Female gametes are called eggs. They are quite large in size when compared with other cells. At the same time, oddly enough, but in terms of the amount of genetic material, such a cell loses twice as much as conventional autosomes (not germ cells). This is due to the fact that eggs 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 the fusion of male and female germ cells to provide a normal diploid (double) set of chromosomes. So the future baby receives signs from both the father and the mother.
How do egg and sperm "meet"?
Male and female reproductive cells are quite small. Most often they find each other in the ampullar part of the fallopian tubes. The matter is not as simple as it may seemfirst glance. This is due to the fact that, in comparison with the lumen of the fallopian tubes, the size of the germ cells is negligible. It is for this reason that a mechanism is needed so that the egg and sperm can find each other. It is called "chemotaxis" (directed movement). Thanks to him, the fertilization of a cell with a male gamete is relatively simple.
What happens after fertilization?
After the sperm and egg merge into a zygote, the development of the embryo begins. In the future, the zygote gradually moves through the fallopian tubes and after 7-10 days 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 still unformed and increases in size rather slowly. Gradually, the body is divided into 3 main tissues - mesoderm, ectoderm and endoderm. Each of them is involved in the formation of various organ systems of the embryo. 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 what happens next is even more important.
When is conception difficult?
Several conditions must be met for successful fertilization to occur. This is very important to know. Today, one of the most common problems is obstruction of the fallopian tubes. With this pathologyfertilization becomes impossible. This is due to the fact that the sperm is simply not able to get to the egg.
Also in recent decades, there has been a decrease in the concentration of germ cells in sperm and a decrease in its total volume. All this leads to the fact that there are simply too few spermatozoa to reach the ampulla of the fallopian tubes.
