Source:? Small and medium-sized enterprise technology story?
The disconnection of umbilical cord after delivery marks that we have become independent individuals and started our own life journey. The scar formed after the umbilical cord falls off is the navel. So, your navel is the first scar in your life. But apart from picking it occasionally, we never paid attention to this scar again. Although the belly button looks useless, this guy is really not simple.
Start with a supermodel without a navel.
Is it true that some people don't have navel? The secret supermodel KK (karolina kurkova) is known as the "Umbilical Supermodel". On the stage, in addition to her outstanding figure and appearance, her "belly button eye" is also extremely eye-catching. Unlike ordinary people's navel, her navel has only a shallow depression.
However, she is really not Eve. The reason why she said "no navel" is because she was once a child with congenital gastroschisis, and her intestines would protrude from the weak point of the abdominal wall. Not long after her birth, she had an operation, and she healed well after the operation, and almost no surgical scars were seen. Moreover, the position where the belly button should have grown out does not look like a belly button because of the influence of surgical scars.
However, strictly speaking, the big "KK" is not without a navel, but the navel is not so obvious. In fact, there is no human without navel in this world. Whether it's a natural delivery or a caesarean section, we will leave a navel scar.
And this is almost all mammals, will have the same characteristics, mainly depends on our viviparous way. The fetus needs to communicate with the mother's placenta through umbilical cord, and umbilical cord scar will inevitably appear after birth. It's just that the degree of healing is different, and the umbilical cord in some animals is difficult to be noticed.
If you pull out your dog or cat's belly, you should find a small scar. That is their navel. Even aquatic mammals such as whales and dolphins have a navel that is not particularly obvious, but as long as you are serious, you can find it.
Dolphins' navel, like marsupials in mammals, actually has umbilical cord. However, because of the short pregnancy time, I will live in a nursing bag in about a month. By the time they say hello to the world, the umbilical cord has naturally fallen off, leaving almost no trace. Therefore, it is difficult for us to find the navel structure from marsupials.
However, platypus and echidna, heterogeneous mammals, theoretically have no navel because they lay eggs. The oviparous animals in amniotic animals can also be said to have a "navel" to some extent. In fact, they are also separated from the outside world by velvet eggs, and the transportation of nutrients naturally needs a link.
The structural diagram of chorionic eggs is 1. Eggshell 2. The outer membrane 3. Intima 4. Egg band 5. Outer protein 6. Intermediate protein 7. Yolk membrane 8. Egg yolk core 9. Embryo disc 10. Yellow yolk 1 1. White egg yolk 12. Endoprotein 65438+.
For example, we can sometimes see a newborn turtle, and its abdomen will have a small yellow drum bag, just like the turtle's small navel. This is actually the yolk sac of the tortoise (that is, the yolk we call it). Generally speaking, they should be completely absorbed by the blastoderm before hatching and fused into a part of the digestive system. However, in some special cases, the yolk sac has not been completely absorbed, and this part of the tissue will remain.
So, whether there is a navel or not depends on how you want to define it. If umbilical cord and placenta are defined, then viviparous animals in mammals theoretically have navel. However, if it is distinguished by the presence or absence of villous eggs, then in theory, amniotic animals have a "navel", including platypus in mammals. Whether the navel is convex or concave really can't blame the midwife. In fact, even between people, the navel is very different. The most obvious difference is the difference between the protruding navel (outy) and the concave navel (inny). Many people may think that it depends on the different skills of midwives when cutting umbilicus. But the midwife really can't hold it. Whether their knot is beautiful or not, every navel has what it should have.
90% of human navel is concave, and the remaining 10% is convex.
Actually, let's look at the method of cutting umbilical cord. The midwife will first seal the umbilical cord on both sides of the incision with surgical forceps, then cut the umbilical cord and clamp it with a plastic umbilical cord clamp. The umbilical cord attached to the baby is also called umbilical cord stump. It will take some time for the midwife to take off the clip. Don't worry, neither mother nor baby will feel pain in this process.
After birth, the baby no longer needs to absorb nutrition or discharge waste from the mother through the umbilical cord. And this residual umbilical cord will slowly lose its function, start to turn black and wither automatically. About a week later, the umbilical cord stump that was originally attached to the baby's navel will automatically fall off. From this process, it doesn't matter whether the midwife cuts horizontally or vertically. Even if the umbilical cord is not cut off on purpose, this little tail can't be kept.
However, the latest scientific research shows that there is no need to worry too much about cutting the umbilical cord. It is more beneficial for the baby to cut the umbilical cord within three minutes or more after birth. Delayed umbilical cord cutting can make the baby absorb 80- 100 ml of nutrition. Letting placenta and umbilical cord blood enter the newborn can reduce the incidence of anemia within six months after birth. Therefore, it is generally recommended to postpone the timing of umbilical cord cutting now. But whether it is cut in advance or delayed, it does not affect the shape of the navel.
From a scientific point of view, an important factor that determines the shape of the navel eye is the healing effect of your wound. At first, most newborns' navel was convex. This is because scar tissue slowly fills the hole from the inside out. With the passage of time, this protruding tissue will gradually form a depressed navel.
However, 65,438+00% infants are difficult to form invagination, thus obtaining prominent umbilical eyes. The reason may be personal scar constitution, poor healing effect, or slight infection at the umbilical cord shedding.
In addition, if the healing situation is very unsatisfactory and the navel is abnormally prominent, umbilical hernia should be considered. When the abdominal pressure increases, there will be a weak umbilical protrusion in the abdominal contents, forming umbilical hernia. Umbilical hernia, if you are not satisfied with the shape of navel when you grow up, someone will modify it through navel plastic surgery. From an aesthetic point of view, the navel is the most attractive small "T".
What's behind the navel? Everyone scratched their belly buttons, right? Although some people worry that it will be torn, almost no one can resist its temptation. So what's it like to dig your navel? Many people describe it as an inexplicable feeling of urine. If you don't believe me, you can lift your coat now, (wash your hands first) and put your finger into your navel to dig ... The navel is obviously just a scar, and it doesn't work anywhere, but why do you have to pee? To know where this urine comes from, we have to go back to the uterus and see what the umbilical cord is attached to.
Umbilical cord is the connecting structure between fetus and placenta, which is filled with Wharton glue. Among these jellyfish, there are three blood vessels, one umbilical vein and two umbilical arteries. Among them, veins bring oxygen-filled blood from the mother to the fetus through the placenta. These two arteries transport oxygen-deficient blood and waste from the baby to the mother through the embryo.
On the cross section of umbilical cord, there are two umbilical arteries in the upper left and right, a umbilical vein in the middle, and an urachal on the far left. In addition to the three umbilical vessels, the umbilical cord also contains other structures in different periods, such as urachal duct and yolk duct. Among them, the urachal duct is the connecting duct between the allantoic sac and the bladder in embryonic stage. Yolk duct refers to the connecting duct between yolk sac and digestive system in embryonic stage.
Schematic diagram of umbilical cord structure in different stages of embryo
Animals evolved from aquatic to terrestrial, and fetal membranes are adaptive structures to complete embryonic development. Before and after embryo development, three sacs will be formed, namely yolk sac, allantoic sac and amniotic sac. Amniotic sac can provide a safe environment for embryos, yolk sac provides nutrition for embryos, and allantois helps to store metabolic waste.
For people, allantois has little effect and belongs to degenerative organ. The tasks of gas exchange and waste excretion are also entrusted to the cooperation between umbilical cord and placenta. The main function of allantois is to provide tissue for the formation of umbilical artery blood vessels. After the formation of umbilical artery and umbilical vein, the allantois completed its historical mission and began to slowly degenerate into urachus. As the embryo continues to develop, the urachal tube will be connected to the top of the bladder during the descent of the bladder.
Generally speaking, the urachus will be completely occluded and degenerate into the median umbilical ligament when it develops to the late embryo. What about the abnormal situation? If the urachal duct is not completely occluded after the fetus is born, the navel will communicate with the bladder, forming urachal fistula. To put it bluntly, it is the navel leaking urine.
In addition, if the yolk duct is not completely closed, it will form a yolk duct fistula. In this case, it is the navel that ejects feces.
Several kinds of urachal atresia are abnormal, including A complete fistula, B external fistula, C bladder diverticulum and D urachal cyst. Why do we have the feeling of peeing when picking navel? There is a theory that this is an incomplete degeneration of urachal duct, part of which is contained in the median umbilical fold and connected with the peritoneum on the surface of bladder. If the navel is too deep, it will also stimulate the bladder and the urine will live. Maybe this pee is just to remind everyone, please don't pick anything.