In order to keep your belly not broken, do you know how hard your belly is?

Everyone knows that our skin (epidermis) is stretched, but the scientific principles behind it are simple and not simple.

There are two reasons for the stretching of the epidermis, with increased cell volume and increased number of cells. However, it was not until recently that scientists revealed the physiological mechanism that the epidermis could stretch under long -term external force, and stem cells played a key role again.

(Photo source: Flickr/ Lincolnblues)

On May 30 this year, a research papers jointly published by the Chinese Academy of Sciences and the Institute of Candidate Medicine Innovation Research Institute further revealed the specific mechanism of stem cells in the process of skin repair.

Related results were published online by the "Frontiers in Cell and Developmental Biology" magazine. All the authors of the dissertation are from Chinese research institutions.

Do you know how hard the skin's self -repair is?

During the pregnancy of pregnant women, the abdomen can increase by 20-30 cm more than in normal state, and the belly is bulging into a ball-shaped shape. We have never heard of which pregnant women have broken the belly. Even those mothers who are pregnant with polyphors can gradually increase with the baby's development.

Gallery copyright picture, not authorized reprint

In the same principle, surgery such as "breast augmentation", "nose pads" and "pulling" in the plastic medical community can be implemented smoothly without causing skin defects, which is also related to the characteristics of skin resistance and stretching. Although the medical community has been enjoying the benefits of the characteristics of the skin, no one can say the specific mechanism.

Until 2020, the research team from Belgium and Britain found the answer to the question, and related research also appeared on the "Nature" magazine. It turned out that the ubiquitous stem cells once again "struggled" to help the skin carry the burden of self -repair. After that, scientists continued to conduct in -depth research on the role of stem cells during skin repair. The results of this research on Chinese scientists reveal several key regulatory factors that play a decisive role in this process.

During the expansion of pregnant women's belly, epidermis is the bottleneck

If we carefully consider the structure of the belly, we can find that its bottom layer is muscle, the middle is a fat -based subcutaneous tissue, and the top layer is skin, including dermis and epidermis. In the above structure, except for the epidermis, it has a strong deformation ability, and it is more than enough to cope with the deformation of pregnancy.

During pregnancy, abdomen and fetal schematic diagram (copyright picture of the gallery, unauthorized reprint)

However, the epidermis is different. Although the epidermis is also extended, the stretching ability of the epidermis should be slowly reflected in the slow stretching process.

In other words, if the woman's belly becomes as big as an in October in an instant, the epidermis may really be broken. (Actually, the leather may not be able to hold it in the later stages of pregnancy. The consequence is to form stretch marks.)

Stretch marks (the copyright picture of the gallery, not authorized reprint)

In surgical surgery and beauty surgery, the ability to stretch the epidermis will also be reflected. For example, the chest skin may have a tightness at first after breast augmentation, but it can quickly restore the smooth and natural appearance after surgery. But what is the mechanism? If you want to figure out this problem, you have to talk about the structure of the skin.

Skin structure and regeneration

As the first barrier of the human body to deal with external pathogens, the contribution of the skin is often ignored. In fact, if there is no skin block, bacteria can easily invade the human tissue in large areas.

The skin is the largest organs of the human body with a certain elasticity. More than that, while giving the external stress on the skin, the skin will also expand, that is, slowly grow.

The skin is mainly composed of three parts: epidermal, base film and leather. Among them, the epidermis is located at the outermost layer, and the stratum corneum, transparent layer, granular layer, spiny layer, and base layer from the outside to the inside are located. Among them, the stratum corneum is the thickest part, and it is also the first -name body of the human body.

The basal membrane is the thinnest layer, sandwiched between the base layer of the epidermis and the leather. The dermis layer is dozens of times thicker than the epidermal layer. It consists of connective tissue and can cushion the pressure and strain of the body. The dermis layer is good, and it has blood vessels, nerves and lymphs that run through it.

Skin and muscle tissue below (the copyright picture of the gallery, unauthorized reprint)

Like the withered and growth of the leaves, the skin is always accompanied by falling off and regeneration, which is closely related to skin stem cells.

Skin stem cells are cells with strong proliferation and differentiation capabilities in the skin, which are closely related to the expansion and repair of the skin. Skin stem cells can produce two different types of cells to participate in division, and they are originally existed in the basal membrane.

After the epidermal stratum corneum falls off, these cells proceed from the base membrane layered and moved from the inside to the outside through the epidermal layer, like a process of spread outward. After multiple differentiation stages, until moved to the epidermal keratin to become a new stratum corneum, it constitutes the complete process of skin metabolism.

This process is about 48 days, so the naked eye is not visible at all.

What changes have happened when stretched?

In addition to the conventional skin regeneration process dominated by skin stem cells, when the sudden mechanical stress, the skin will resist such changes by adjusting its size and shape to maintain the skin as the function of the human body's first barrier.

Clinically, doctors buried the inflatable "skin dilatator" into the skin and slightly expand it, so that the skin covered up to feel tiny stress and promote the skin to regenerate and stretch faster. Different types of skin expansion

(Picture source: reference document 5)

This "skin expansion" provides research on Belgium and British scientists. They injected a similar inflatable hydrogel under the skin of the model mice to give the skin proper expansion stress, and to the epidermal cells The reaction was observed in detail.

Initially, the volume of mouse epidermal cells expanded and the density within the skin unit area decreased, which seemed to be a "expedient measure" for the skin for emergency. After all, it is not difficult to increase the volume of cells, but it takes a certain amount of time to increase the number of cells.

Since then, scientists have found that stem cells have perceived the external stress and their own abnormality during the basis of the basal membrane and upward movement. After that, these stem cells will pass this perception to adjacent stem cells and promote their brief self -renewal and division to cope with the lack of possible cells that may occur.

The proliferation and differentiation of mouse skin when stretching stem cells are proliferated and differentiated

(Picture source: reference 3)

This is like a switch and a key that turns on the proliferation mode on each stem cell. When they perceive the stress, the stem cells that are originally in the normal working mode will use the key to turn on the proliferation switch of the stem cell next to the next stem cells to make them briefly changes. To increase the number of cells to increase the number of cells, thereby accelerating the regeneration of skin cells.

It is worth mentioning that researchers have also found that not all stem cells respond to external stretching, and only some specific stem cells will respond.

The reason why these wonderful discoveries can be stretched after the skin can be stretched out of the skin:

When suffering from external forces, skin cells can perceive stress and react -epidermal cells will adjust their own shapes, and then some specific skin stem cells will split and proliferate briefly to expand the number of cells, thereby maintaining the original integrity of human skin.

It can be imagined that the reason why the skin on the belly of pregnant women has not ruptured due to expansion because of the deformed expansion of the belly skin cells and the increase in the number of cells caused by stem cell proliferation to make the skin as tough as rubber membrane.

The latest research results confirmed the omnidirectional of skin stem cells, and also revealed the reasons behind the skin's superb skin repair ability after surgery. For the plastic surgery industry, this research also objectively provides a certain theoretical basis for various plastic surgery. However, there are individual differences in physical fitness, and beauty medical institutions also have a difference in level and experience. Before choosing cosmetic surgery, you must do a good job of investigating and preparing.

Author: Yu Xiaoli

references:

[1] Nature: It has been used in plastic surgery for more than 60 years. The principle is this kind of https://xw.qq.com/cmsid/20200809A0G1S800

[2] Stretch Exercises for STEM Cells Expand the Skin Stretch Exercises for STEM Cells Expand the Skinhttps: //www.nature.com/artICles/d41586-02158-Y

[3] Mechaanisms of Mechanical-Stretch-IDuced Skin Expansion Revealedttps: //Medicalxpress.com/news/2020-07-Mechaanical-duced-SKINALEVANAINAINAINAINAINAINAINAININININININININININININININININININININININININININININININININININININININININININININININION-Rexpans

[4] Mechanisms of Stretch-Mediated Skin Expansion at Single-Cell Resolutionhttps: //www.nature.com/articleS/S41586-020-2555-7-7

[5] Trebuáová, Marianna, et al. "New Technologies of Tissue Expansion-Review Article."

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