Many pregnant mothers can t tell what is a gestational sac, what is a yolk sac, and what are the dif

Introduction: Most pregnant mothers will have a prenatal examination during pregnancy, and B-ultrasound is one of the prenatal examinations, and most pregnant mothers will see a gestational sac when they look at the results of B-ultrasound. But you can't see the fetal bud and fetal heartbeat, and pregnant mothers should learn some relevant knowledge about this kind of problem, so as to have a clear understanding of the baby's growth and development.

So the topic I want to share today is that most pregnant mothers can't tell what is a gestational sac and what is a yolk sac, and what are the differences between them?

1. What is a gestational sac? What is a yolk sac?

The gestational sac is the original placental tissue, the embryo encased by the vascular amniotic membrane. And after the gestational sac appears, the fetus has not yet been fully formed, but the embryo has already shown a fetal heartbeat. Moreover, the gestational sac is also a product of ectopic pregnancy, and the gestational sac can only be seen in the early stages of pregnancy.

Women who have stopped menstruating for 35 days can see the gestational sac in the uterine cavity. The yolk sac is the gastrum inside the embryo and the yolk sac outside the embryo after embryogenesis, and will contain a large amount of yolk. The yolk sac is mainly a membranous sac that surrounds the abundant blood vessels outside the yolk in the embryo body, and once it exceeds the centimeter, it is called the corpus luteum cyst.

2. What is the difference between a gestational sac and a yolk sac?

The gestational sac is on the outside and the yolk sac is on the inside, while most of the hormones of the embryonic egg are provided by the yellow sac, which is not food for the gestational sac. If there is no echo of pregnancy during the examination, fetal buds and beats are not found. If you want to see the yolk sac, you must first see the gestational sac.

Before the embryo is examined, the yolk sac is seen. As the pregnancy progresses, the yolk sac gradually disappears. Moreover, the gestational sac and the yolk sac are completely different, and the gestational sac can be understood as a small embryo, and in the early stages of pregnancy, the embryo sac is examined by ultrasound.

After that, the yolk sac will appear, and with the yolk sac, the embryo will be able to develop healthily. All in all, the yolk sac and the gestational sac are two completely different substances that can only be detected by ultrasound, and they appear in different sequences.

The yolk sac is formed by the embryo after the body fold, and there is a large amount of yolk in it, so it is called the yolk sac, and the difference between the gestational sac and the gestational sac is: the gestational sac is a sac that wraps all tissues, while the yolk sac is inside the gestational sac.

It is a kind of cyst described in the process of embryogenesis and development, and the difference with the gestational sac is that the location found is different, the gestational sac generally appears in the first trimester, and the yolk sac generally appears in the later stage.

After the embryo has a body fold, the gastrula is clearly divided into the gastrula in the embryo and the yolk sac outside the embryo, which contains a large amount of yolk, and the wall of the yolk sac is formed by the extraembryonic endoderm and the extraembryonic mesoderm. Mature follicles form the corpus luteum after ovulation. In the angiogenesis phase, blood flows into the corpus luteum cavity (corpus luteum hematoma), so in the normal state, the corpus luteum is cystic, and in the pathological case, if its diameter is, it is called cystic corpus luteum; If it is exceeded, it is called a corpus luteum cyst.

Normally, according to ultrasound, whether to judge whether to be pregnant, in addition to the fetal bud in the gestational sac to measure the fetal heartbeat, is to see the yolk sac in the gestational sac, some yolk sac and fetal heart appear relatively late, after a period of time to see again, if there is still not, it is estimated that it can not be wanted.

The following is an introduction to the yolk sac:

Yolk sac (yolk sac) After the embryo has a body fold, the gastrula is clearly divided into the gastrum in the embryo and the yolk sac outside the embryo, which contains a large amount of yolk sac, and the wall of the yolk sac is formed by the extraembryonic endoderm and the extraembryonic mesoderm. A membranous sac with abundant blood vessels located in the ventral area of the embryonic body and surrounded by the yolk. The constricted part that communicates with the midgut of the embryonic body is called the yolk stalk.

The cyst wall is made up of the outer endoderm of the inner layer and the outer layer of the extraembryonic mesoderm. The eggs of reptiles and birds are rich in yolk, and the yolk sac is large, which has the function of storing, decomposing, absorbing and transporting nutrients. The yolk sac gradually shrinks as the embryonic body grows and the yolk is depleted, and is eventually absorbed into the body and fuses to form part of the small intestine.

The eggs of lower mammals are rich in yolk, and their yolk sac is quite developed; The eggs of viviparous mammals are oligoyoll, and their yolk sacs are small and do not contain yolk. At the end of the 5th week, the yolk sac of the human embryo is severed from the gastrum and gradually degenerates, and by the 7th week, it becomes a small sac with a diameter of less than 5 mm, which remains on the surface of the placenta. The occurrence of the yolk sac of the human embryo is also one of the phenomena of repetition phylogenesis.

The extraembryonic mesoderm on the human yolk sac forms many blood islands at the third week, which is the earliest part of the embryo to form blood vessels and blood cells, and is the hematopoietic site of the early embryo (10 weeks ago), and the yolk sac artery and vein will be involved in the formation of mesenteric artery and hepatic portal vein. Since the primitive germ cells also appeared in the wall of the yolk sac at the earliest, the yolk sac is the original origin of the germ cell. The yolk sac can also be found in other vertebrates and molluscs cephalopods.

Hello, your friend's inspection is normal, now it's observation.

After pregnancy, there must be a yolk sac, and there will be a fetal heart and fetal bud in the yolk sac, which is not easy to detect when you first go for an examination, so you can wait until about 3 months of pregnancy to do the examination.