Fertilization is a process that is the fusion of male and female germ cells. It would seem that there is nothing so complicated in it, but in reality the situation is somewhat different. Fertilization is not an instantaneous process.
What are the characteristics of germ cells, and why are they needed?
Female gametes are called ova. 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 to ordinary autosomes (not sex cells). This is due to the fact that eggs are formed due to meiosis, and not mitosis, like the rest. A similar mechanism for the creation of gametes is simply necessary, since this allows the normal diploid (double) set of chromosomes to be provided when the male and female germ cells merge. So the future baby receives signs from both the father and the mother.
How do the ovum 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. This 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 size of 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 (directional movement). Thanks to him, fertilization of the cell with a male gamete is relatively simple.
What happens after fertilization?
After the sperm and egg merge into a zygote, embryo development begins. Subsequently, the zygote gradually moves through the fallopian tubes and after 7-10 days enters the uterine cavity. There, the embryo invades its wall and begins to receive nutrition from the mother's body. Over the next few weeks, it remains unformed and grows in size quite slowly. Gradually, the body is divided into 3 main tissues - the 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, since this can lead to significant defects in its formation. So, fertilization is a very difficult process, but everything that happens in the future is even more important.
When is it difficult to conceive a child ?
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 pathology, fertilization 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 semen and a decrease in its total volume. All this leads to the fact that sperm are simply too few to reach the ampullar part of the fallopian tubes.