The yolk sac: what is it? Functions and significance of the yolk sac in pregnancy

Many pregnant women are interested in questions about what functions the yolk sac performs, what it is and when it occurs. After all, it's not a secret for anyone that this is an extremely important element that ensures the normal development of the embryo.

What is the yolk sac ?

During the ultrasound examination in the early stages of pregnancy, the doctor pays attention to the size and development of this particular structure. The yolk sac is a special extraembryonic organ that forms at the initial stages of pregnancy and performs extremely important functions in the first months. It is located in the region of the umbilical cord and is closely associated with the embryonic gut. This formation is formed from mesoderm cells and has the form of a ring with thin walls.

The main functions of the yolk sac

In fact, this education is extremely important. At the initial stages of development, the embryo and yolk sac are closely related. First, this structure is a source of nutrients. Secondly, the yolk sac actively participates in the process of breathing.

Approximately on the eighteenth day of pregnancy in the yolk sac the first red blood cells begin to form. This structure also ensures the formation of the first capillaries, from which the fetal circulatory system will develop in the future.

On the 28th day, the first sex cells are formed in the walls of the sac, which later become the main for the development of the gonads and the reproductive system of the child. In addition, the yolk sac during the first six weeks performs the functions of the liver: it is in its tissues that all dangerous substances and toxins are retained.

Apparently, this formation is extremely important for the normal development of the fetus. If the yolk sac does not function normally, then it threatens to spontaneously terminate the pregnancy.

Where does the yolk sac go?

Every future mother knows that during pregnancy the vital activity of the fetus depends on the functioning and condition of the placenta. But where does the yolk sac go? In the first three months, the embryo and placenta have time to fully develop. At this stage, the formation of the placental type of circulation is completed, and the yolk sac is no longer needed. His tissues are gradually reduced. Until the end of pregnancy, this formation is preserved as a small cyst located near the umbilical cord.

Is it dangerous to increase the yolk sac?

Since this structure is very important, it is only natural that it is examined during an ultrasound examination. You can see it from the sixth week after conception. At the 12th week of pregnancy, the yolk sac can no longer be examined with ultrasound.

At 5-10 weeks the size of the bag should not exceed 5.5 millimeters. But in women, pregnant 8-12 weeks, the size of this formation, as a rule, is about 2 mm.

But sometimes the doctor notices that the yolk sac is enlarged. What does this mean and how dangerous? In fact, any deviation from the norm may indicate a threat to pregnancy. Naturally, this is not the final diagnosis, since other, additional studies are needed. For example, an increase in yolk sac may be associated with eating, taking certain medications, or with severe stress. In any case, with similar results, ultrasound should be poisoned by a gynecologist. Only a specialist knows why the yolk sac can be enlarged, what this means and whether special treatment is required.