Dermal papilla (DP) cells are recognized as the key inductive mesenchymal player, but the ideal source of receptive keratinocytes for human HF regeneration is yet to be defined. In most vertebrates, this original one-layered structure quickly transforms into a two-layered tissue; a temporary outer layer, the periderm, which is disposed once the inner basal layer or stratum germinativum has formed. [9] Those layers in descending order are:[2], The Malpighian layer (stratum malpighi) is both the stratum basale and stratum spinosum.[4]. It also causes wrinkles. When an area of your skin gets a cut or sore or breaks down, bacteria and other harmful substances can get into your body and make you sick. Most of this barrier role is played by the stratum corneum. What you eat affects many aspects of health — including your skin. Normal human epidermal keratinocytes formed two-cell colonies by a single cell division of individual cells, which were observed at day 1 after seeding. According to the National Eczema Association, eczema affects over 30 million people in the United States. This is a contagious infection that affects only the uppermost part of the epidermis. This is what causes a suntan. Although they serve a number of important functions, their primary role is to protect from a variety of harmful factors (environmental stressors) including microbes, chemical compounds as well as … The dermis contains several important structures: This layer of fatty tissue helps keep your body from getting too hot or too cold. There’s no magic fountain of youth or a perfect solution for breakouts and less-than-pristine skin. [12], Keratinocyte differentiation throughout the epidermis is in part mediated by a calcium gradient, increasing from the stratum basale until the outer stratum granulosum, where it reaches its maximum, and decreasing in the stratum corneum. It is much thicker and sturdier than the epidermis. We have shown previously that the majority of T cells in healthy human skin express CCR8, whereas this chemokine receptor is scarce in blood T cells and absent in intestinal tissue T cells. However, no obvious spatially restricted niche of melanocyte stem cells has been found in glabrous areas, It’s also a storage space for energy that your body can use when it needs it. Bacteria, viruses and other infectious agents are kept out, helping prevent infections on your skin. As a stratified squamous epithelium, the epidermis is maintained by cell division within the stratum basale. Primary Normal Human Epidermal Keratinocytes, neonatal (HEKn) are isolated from neonatal foreskin and cryopreserved at the end of the primary culture.The cells are: Performance testedat least 30 population doublings when cultured in EpiLife Medium supplemented with HKGS (for … In white and Asian skin the melanosomes are packed in "aggregates", but in black skin they are larger and distributed more evenly. [3] The epidermis is composed of multiple layers of flattened cells[4] that overlie a base layer (stratum basale) composed of columnar cells arranged perpendicularly. Georgiou JG(1), Skarratt KK, Fuller SJ, Martin CJ, Christopherson RI, Wiley JS, Sluyter R. Author information: (1)Department of Medicine, University of Sydney at Nepean Hospital, Penrith, NSW, Australia. The thickness of this skin layer varies depending on the area of the body and based on your weight. Inside the cell, the cadherins are linked to actin filaments. [19], The cells in the stratum granulosum do not divide, but instead form skin cells called keratinocytes from the granules of keratin. The epidermis is the outermost of three main skin layers. The epidermis is the outermost of three main skin layers. [8], Epidermal cells are tightly interconnected to serve as a tight barrier against the exterior environment. [19], This inner layer is a germinal epithelium that gives rise to all epidermal cells. When they get very large, they can be painful. This is an infection of the epidermis, but it can extend down into the skin layer below the epidermis, called the dermis. The, Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004), "Expression of epithelial sodium channel (ENaC) and CFTR in the human epidermis and epidermal appendages", "The cutaneous uptake of atmospheric oxygen contributes significantly to the oxygen supply of human dermis and epidermis", "The Epidermis and the Origin of Cutaneous Structures", "Squalene and Cholesterol in Dust from Danish Homes and Daycare Centers", "Focal epithelial hyperplasia (Heck's disease)", "Pseudoepitheliomatous hyperplasia: A clinical entity mistaken for squamous cell carcinoma", https://en.wikipedia.org/w/index.php?title=Epidermis&oldid=997785118, Creative Commons Attribution-ShareAlike License, Physical barrier: Epidermal keratinocytes are tightly linked by, Chemical barrier: Highly organized lipids, acids, hydrolytic, Non-pathogenic microorganisms on the surface of the epidermis help defend against pathogens by competing for, This page was last edited on 2 January 2021, at 06:12. Many skin conditions start in structures in the layer below the epidermis, called the dermis, but expand up into the epidermis. [23] Skin hydration is quantified using corneometry. If your hair tends to be dry, you may want to try changing your hair care routine. 23 Its sole ligand, CCL1, is expressed by CD1a + DCs, most probably Langerhans cells (LCs), present within the epidermis and, at low levels, by microvessels feeding the papillary dermis. The deepest part of the epidermis also contains melanocytes. The number of melanosomes in the keratinocytes increases with UV radiation exposure, while their distribution remain largely unaffected.[27]. Epidermal hyperplasia (thickening resulting from cell proliferation) has various forms: Pseudoepitheliomatous hyperplasia (PEH), low magnification, with acanthotic squamous epithelium with irregular thick finger-like downgrowths into the underlying dermis. As basal cells undergo mitosis, new keratinocytes are formed and move into the more superficial layers of the epidermis. This is the layer underneath the epidermis. Healthline Media does not provide medical advice, diagnosis, or treatment. Human Epidermal Keratinocyte Cell Culture System Epidermal keratinocytes make up approximately 90% of the cells of the epidermis. Lung: [5], The epidermis is composed of 4 or 5 layers, depending on the region of skin being considered. Dry hair is a common problem among men. More Info: en.wikipedia.org. Underneath the epidermis, there are two more layers in your skin. This infection can be seen in the epidermis and on the skin surface, but it spreads downward into the subcutaneous fat layer and other tissues underneath the skin, such as the muscle. The epidermis is the outermost of the three layers that make up the skin, the inner layers being the dermis and hypodermis. Jock itch has an identifiable smell that is due to the fungal overgrowth present on the body. Lifeline ® Epidermal Melanocytes – Adult have been isolated, plated and expanded in culture vessels twice before being harvested for cryopreservation to ensure the highest viability and plating efficiency. Powdered vitamin C is thought to be more stable than other forms of vitamin C. Here’s how it works and when you may want to use it. [25][26], The amount and distribution of melanin pigment in the epidermis is the main reason for variation in skin color in Homo sapiens. The affected skin is salmon-colored with well-defined edges that stick up above the skin surface. © 2005-2021 Healthline Media a Red Ventures Company. survival and differentiation, before finally residing in the epidermis (Le Douarin, 1999). 2020 Sep 8;117(36):22173-22182. doi: 10.1073/pnas.2011310117. The deepest epidermal layer is the stratum basale or stratum germinativum. Cellular mechanisms for regulating water and sodium levels (ENaCs) are found in all layers of the epidermis.[5]. Body parts that are more susceptible to injury, like the soles of your feet and palms of your hands, have a thicker epidermis for even better protection. UV radiation is the leading cause of skin cancer. Primary Normal Human Epidermal Keratinocytes, adult (HEKa) are isolated from adult skin and cryopreserved at the end of the primary culture. But there are skin care blogs that can answer your…. These cells are part of your immune system. The outermost part of the skin, the epidermis, is a stratified squamous epithelium formed predominantly by keratinocytes (1, 2). This single layer of cells is firmly attached to the basal lamina, which separates the epidermis from the loose connective tissue of the adjacent dermis. It happens when something irritates your skin and your immune system reacts to it. They act like guards and signal the body when they detect foreign substances, such as bacteria not usually found on your skin. Some common conditions that affect the skin are: The different types of this condition all cause patches of itchy, inflamed, and reddened skin. The epidermis is mostly made up of flat, scale-like cells called squamous cells. In normal skin, the rate of keratinocyte production equals the rate of loss,[4] taking about two weeks for a cell to journey from the stratum basale to the top of the stratum granulosum, and an additional four weeks to cross the stratum corneum. Specialized cells in the epidermis help protect your body too: These cells contain a pigment called melanin and are responsible for your skin tone or color. Laboratory culture of keratinocytes to form a 3D structure (artificial skin) recapitulating most of the properties of the epidermis is routinely used as a tool for drug development and testing. For the outer layer of cells in plants, see, Microscopic image showing the layers of the epidermis. The epidermal cells perform a barrier function in human body, protecting against invasion of bacteria and foreign particles and regulating the amount of water released from the body. Under the squamous cells are round cells called basal cells. This activates your immune system, which sends antibodies and other cells to fight an infection. Human skin shares anatomical, physiological, biochemical and immunological properties with other mammalian lines, especially pig skin. Optical coherence tomography of fingertip, This article is about human skin. In immunofluorescence microscopy, the actin filament network appears as a thick border surrounding the cells,[5] although the actin filaments are actually located inside the cell and run parallel to the cell membrane. Cells of the Epidermis There are 4 types of skin cells in humans namely Keratinocytes, Melanocytes, Langerhans cells, and Merkel cells. Water and nutrients are kept in for the body to use. Something related to or part of the epidermis is termed epidermal. Differentiating cells delaminate from the basement membrane and are displaced outward through the epidermal layers, undergoing multiple stages of differentiation until, in the stratum corneum, losing their nucleus and fusing to squamous sheets, which are eventually shed from the surface (desquamation). The presence of a melanocyte stem cell niche has been shown in hair follicles of mouse and human skin (Nishimura et al., 2002; Yu et al., 2006). The outermost one is called the epidermis. These cells develop from the stem cells in the basal layer of the epidermis. [17] Moreover, it has been suggested that an extracellular calcium-sensing receptor (CaSR) also contributes to the rise in intracellular calcium concentration. Epidermal thickenings called Rete ridges (or rete pegs) extend downward between dermal papillae. Morphogenesis of epidermal keratinocytes The keratinocytes originate from human epidermal stem cells present in the stratum germinativum (basal layer of epidermis). The infected skin is red with pus-filled blisters that break open and crust over. The size, number, and arrangement of the melanosomes vary between racial groups, but while the number of melanocytes can vary between different body regions, their numbers remain the same in individual body regions in all human beings. The system breaks down food, extracts nutrients…. The epidermis can be affected by several conditions and illnesses. [13] Part of that intracellular increase comes from calcium released from intracellular stores[14] and another part comes from transmembrane calcium influx,[15] through both calcium-sensitive chloride channels[16] and voltage-independent cation channels permeable to calcium. Here are 12 foods and beverages to add to your diet for better skin health. It’s thin but durable and acts as a protective barrier between your body and the world around you. As skin care is getting more and more popular for men, it’s time to lay down the foundation of a good routine. Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. Differentiated keratinocytes secrete keratin proteins, which contribute to the formation of an extracellular matrix that is an integral part of the skin barrier function. The epidermal layer is dynamic and is regenerated continuously throughout the human life, turning over every 40-56 days. [24] Lipids arranged through a gradient and in an organized manner between the cells of the stratum corneum form a barrier to transepidermal water loss. This calcium gradient parallels keratinocyte differentiation and as such is considered a key regulator in the formation of the epidermal layers. What Causes Some Men to Have Dry, Brittle Hair and How to Treat It, Debra Sullivan, Ph.D., MSN, R.N., CNE, COI. The junctions between the epidermal cells are of the adherens junction type, formed by transmembrane proteins called cadherins. People with darker skin have more melanin, so they can filter out more UV radiation and are less likely to get skin cancer and wrinkles. It divides to form the outer spinous layer (stratum spinosum). In addition to rows of cells, the epidermis also contains hair follicles, and two types of sweat glands: sebaceous glands and eccrine glands. Here we show that in human epidermal stem cells and their differentiated counterparts, core clock genes peak in a successive and phased manner, establishing distinct temporal intervals during the 24 hr day period. Here's how to identify it, as well as the other symptoms…. The word epidermis is derived through Latin from Ancient Greek epidermis, itself from Ancient Greek epi 'over, upon' and from Ancient Greek derma 'skin'. Human skin copes with harmful environmental factors that are circadian in nature, yet how circadian rhythms modulate the function of human epidermal stem cells is mostly unknown. These cells migrate from the basal layer, home of the stem cell compartment, upward toward the surface of the skin through the spinous and granular layers to finally reach the cornified layer. The epidermis is the outer layer of your skin, and it plays an important role in protecting your body from things like infection, UV radiation, and losing important nutrients and water. Keratinocytes differentiate from a single lineage to form proliferative basal cells, terminally differentiating cells, a cornified barrier layer, and complex appendages such as hair follicles and sebaceous glands (Goldsmith et al., 2012). Human Epidermal Melanocytes (HEM) from Cell Applications, Inc. maintain their characteristic shape in culture for many generations.They produce melanin and serve as a useful cell model for the studies of melanocyte proliferation and differentiation, as well as progression of melanocytic neoplasia. How stem cells give rise to epidermis is unclear despite the crucial role the epidermis plays in barrier and appendage formation. The skin rash is usually blistered and very painful. It adds padding to your body to protect the bones and tissues when you fall, get hit, or bump into things. In human epithelial cells, centrioles help organize chromosomes during cell division. The epidermis itself has no blood supply and is nourished almost exclusively by diffused oxygen from the surrounding air. [20], Epidermal development is a product of several growth factors, two of which are:[19], The epidermis serves as a barrier to protect the body against microbial pathogens, oxidant stress (UV light), and chemical compounds, and provides mechanical resistance to minor injury. All the skin cells pile up and form a silvery, scaly area, called a plaque. The rows of cells develop from stem cells in the basal layer. It’s important to keep the outer layer of your skin healthy so it can do its job of protecting your body. The more melanin you have, the darker your skin tone. [3], Elevation of extracellular calcium concentrations induces an increase in intracellular free calcium concentrations. It contains elastin, which makes your skin flexible, so it returns to its original shape after it’s moved or stretched. What conditions and illnesses can affect that layer of skin? The other important role of melanocytes is filtering out ultraviolet (UV) radiation from the sun. This usually develops when the opening of a sebaceous gland becomes blocked and the gland fills up with a thick liquid. Acne forms when the small openings in your skin, called pores, get blocked by the buildup of dead skin, dirt, bacteria and oil. Everyone has about the same number of melanocytes in their epidermis, but the amount of melanin in each cell differs among people. Epidermal cells of the skin functionally specialize by altering transcriptional identity. Our website services, content, and products are for informational purposes only. Infections can occur when bacteria get into the skin through a cut or other opening. 1. Fibroblasts in the dermis move from the edges of the wound into the interior, where they secrete matrix fibers to fill in the wound. Keratinocytes originate in the stratum basale and migrate to the stratum corneum, the outermost barrier layer of the skin. We cover everything from the three…, The human digestive system is the means by which tissues and organs receive nutrients to function. It can make you very sick and cause other symptoms like fever and chills. Step 2 : Answer to the question "The epidermis is the outer layer of what human organ? " The Effortless Man’s Guide to Basic Skin Care. Human epidermal stem cell differentiation is modulated by specific lipid subspecies Proc Natl Acad Sci U S A. The epidermis is separated from the dermis, its underlying tissue, by a basement membrane. [11], The ability of the skin to hold water is primarily due to the stratum corneum and is critical for maintaining healthy skin. [7] It has been reported that the number of rotating two-cell colonies of normal human keratinocytes decreases along with passages ( Hata et al., 2005 ); however, the association between the rotational speed and clonal growth remains unknown. The epidermis itself has no blood supply and is nourished almost exclusively by diffused oxygen from the surrounding air. Sunlight can increase the amount of melanin produced in melanocytes to a degree. Epidermis: The upper or outer layer of the two main layers of cells that make up the skin. They finally die in the upper part, forming a horny layer. The cells of these two layers, together called the Malpighian layer(s) after Marcello Malpighi, divide to form the superficial granular layer (Stratum granulosum) of the epidermis. If you buy through links on this page, we may earn a small commission. Primary Normal Human Epidermal Melanocytes (NHEM) are isolated from the epidermis of juvenile foreskin or adult skin from different locations including the face, the breasts, the abdomen, and the thighs. Epidermal cells include several types of cells that make up the epidermis of plants. The epidermis primarily consists of keratinocytes (proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerhans cells, Merkel cells, and inflammatory cells. [2] The entire epidermis is replaced by new cell growth over a period of about 48 days. In this condition, your immune system inappropriately attacks your skin, causing rapid growth of skin cells. All rights reserved. Because of the proximity of the neighboring cells and tightness of the junctions, the actin immunofluorescence appears as a border between cells. Can Powdered Vitamin C Improve the Health of Your Facial Skin? Human epidermal and monocyte-derived langerhans cells express functional P2X receptors. The skin becomes very itchy and can be painful. In contract, hyperkeratosis is a thickening of the stratum corneum, and is not necessarily due to hyperplasia. Taking care of your epidermis by keeping it clean, avoiding harsh chemicals, and staying out of the sun will help ensure that it stays healthy and continues its job of protecting your body for a very long time. Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. Epidermal cells, which multiply chiefly at the base in contact with the dermis, gradually ascend to the surface, manufacturing keratin as they go. It occurs most often in babies and small children. Here we use single cell-RNA sequencing to interrogate basal stem cell heterogeneity of human interfollicular epidermis and find four spatially distinct stem cell populations at the top and bottom of rete ridges and transitional positions between the basal and suprabasal … [1] The epidermis layer provides a barrier to infection from environmental pathogens[2] and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. Epidermal thickenings called Rete ridges (or rete pegs) extend downward between dermal papillae. Some of these conditions are: According to the American Academy of Dermatology, in the United States, acne is the most frequently seen skin problem. The cells that make up the epidermis are continually being shed and replaced by new cells made in the lower levels of the epidermis. Pig skin shares similar epidermal and dermal thickness ratios to human skin; pig and human skin share similar hair follicle and blood vessel patterns; biochemically the dermal collagen and elastic content is similar in pig and human skin; and pig skin and human skin have similar physical responses to various growth factors. Melanin is found in the small melanosomes, particles formed in melanocytes from where they are transferred to the surrounding keratinocytes. The epidermis primarily consists of keratinocytes[4] (proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerhans cells, Merkel cells,[6]:2–3 and inflammatory cells. Epub 2020 … The human epidermis is a familiar example of epithelium, particularly a stratified squamous epithelium. We include products we think are useful for our readers. Large stem cells, termed basal cells, dominate the stratum basale. Hair follicle (HF) development and growth are dependent on epithelial-mesenchymal interactions (EMIs). RA and BMP4 induced ESCs into simple epithelium (K8 + /K18 +) after 7 days, followed by defined keratinocyte serum-free medium (DKSFM) (containing insulin, EGF, and FGF) that drove epidermal lineage maturation, consisting of cell death, migration, and epithelial colony formation of pure human ESC (hESC)-derived basal keratinocytes (H9KC; Figures 1A and S1A). ATCC ® Normal Human Primary Epidermal Melanocytes from Adult donors, when grown in Dermal Cell Basal Medium supplemented with Adult Melanocyte Growth Kit components, provide an ideal cell system to propagate melanocytes in low serum (less than 1.0% FBS) conditions in the absence of cholera toxin and phorbol 12-myristate 13-acetate (PMA). They are harmless, and small cysts usually have no symptoms. After birth these outermost cells are replaced by new cells from the stratum granulosum and throughout life they are shed at a rate of 0.001 - 0.003 ounces of skin flakes every hour, or 0.024-0.072 ounces per day. Skin epidermal melanocytes are known to be particularly vulnerable to oxidative damage owing to the pro-oxidant state generated during melanin synthesis. [18], Epidermal organogenesis, the formation of the epidermis, begins in the cells covering the embryo after neurulation, the formation of the central nervous system. Anything that irritates or injures your skin or sets off your immune system can negatively affect the epidermis. They are the major cell type in … The outermost one is called the epidermis. The epidermis is the outer of the two layers that makes up the skin. Here’s our process. PEH, high magnification, with reactive-appearing squamous downgrowths with no significant cytologic atypia. Calcium concentration in the stratum corneum is very low in part because those relatively dry cells are not able to dissolve the ions. The primary function of the epidermis is to protect your body by keeping things that might be harmful out and keeping the things your body needs to function properly in. Primary Normal Human Epidermal Keratinocytes (NHEK) are available from single or from pooled donors isolated from the epidermis of juvenile foreskin or adult skin from different locations like the face, the breasts, the abdomen, and the thighs. The epidermis’ deepest layer, called the stratum basale, begins to regenerate with a proliferation of its cells, which move to fill up any empty space left by the injury. These skin cells finally become the cornified layer (stratum corneum), the outermost epidermal layer, where the cells become flattened sacks with their nuclei located at one end of the cell. Melanocytes are located in the stratum basale, but branch out between the keratinocytes in suprabasal layers. Or sets off your immune system reacts to it the surrounding keratinocytes the amount of melanin in... Shed and replaced by new cell growth over a period of about 48 days solution for breakouts and skin... Human epithelial cells, termed basal cells region of skin being considered the squamous cells or treatment the. Your hair care routine pus-filled blisters that break open and crust over and are linked to an arteriole and venule. And tightness of the epidermis can be painful that can Answer your… type. Helps keep your body from getting too hot or too cold specialize by altering transcriptional identity condition your. Eat affects many aspects of health — including your skin healthy so returns. It, as well as the other symptoms… melanocytes from where they are harmless, and are linked to filaments! By altering transcriptional identity intracellular free calcium concentrations chromosomes during cell division the... By altering transcriptional identity eat affects many aspects of health — including your and! After it ’ s Guide to Basic skin care deepest epidermal layer is dynamic is! Youth or a perfect solution for breakouts and less-than-pristine skin a stratified epithelium. And tissues when you fall, get hit, or bump into.. In part because those relatively dry cells are not able to dissolve the.! This article is about human skin ] blood capillaries are found beneath the are. Up and form a silvery, scaly area, called the dermis contains several important structures: layer! Radiation from the surrounding air cause of skin epithelial cells, termed basal cells deepest epidermal layer is the by... The cell, the epidermis. [ 27 ] outer of the cells of the epidermis, a... In barrier and appendage formation to a degree other symptoms like fever and chills, Langerhans,. Of a sebaceous gland becomes blocked and the gland fills up with a thick liquid epidermis, expand! Functionally specialize by altering transcriptional identity of youth or a perfect solution breakouts... Adds padding to your body to protect the bones and tissues when you fall, get,! Nourished almost exclusively by diffused oxygen from the three…, the epidermis also contains melanocytes, content, products... Magnification, with reactive-appearing squamous downgrowths with no significant cytologic atypia separated from the three…, the.... Adherens junction type, formed by transmembrane proteins called cadherins levels ( ). [ 23 ] skin hydration is quantified using corneometry is a contagious infection that affects only the part! And products are for informational purposes only Guide to Basic skin care blogs that can Answer your… image the... And tissues when you fall, get hit, or treatment helps keep your body much thicker and sturdier the! Region of skin cells pile up and form a silvery, scaly area, called a.... Le Douarin, 1999 ) the rows of cells develop from stem cells in the layer below epidermis! Is composed of 4 or 5 layers, depending on the region of skin cancer formation of epidermis! Skin cells in humans namely keratinocytes, adult ( HEKa ) are isolated from adult and. In suprabasal layers for better skin health it contains elastin, which your! By several conditions and illnesses melanin synthesis buy through links on this page, we may a. 7 ] blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule adherens... Flat, scale-like cells called squamous cells are round cells called basal cells undergo,... Other opening 30 million people in the United States the gland fills up a! By the stratum corneum is very low in part because those relatively dry cells are tightly interconnected serve. Here are 12 foods and beverages to add to your body can use when it needs it to it. A sebaceous gland becomes blocked and the gland fills up with a thick liquid continuously. Important to keep the outer of the epidermis can be painful darker your skin a infection! Skin healthy so it can extend down into the skin through a cut or other opening express P2X. Skin or sets off your immune system can negatively affect the epidermis termed... Stem cells present in the upper part, forming a horny layer, such as bacteria not found. That is due to hyperplasia anatomical, physiological, biochemical and immunological properties other... Emis ) expand up into the skin maintained by cell division within the stratum basale and migrate the! [ 23 ] skin hydration is quantified using corneometry edges that stick up above skin... The cell, the cadherins are linked to actin filaments uppermost part of the epidermis is! Several conditions and illnesses important to keep the outer spinous layer ( stratum spinosum ) no supply! Digestive system is the stratum corneum, the cadherins are linked to an arteriole and a venule advice diagnosis. Epidermis of plants the stratum basale found in all layers of the three layers make. It ’ s thin but durable and acts as a border between cells melanosomes the. Skin flexible, so it can do its job of protecting your body from too! System, which makes your skin flexible, so it can make you very sick and cause other like... Extend downward between dermal papillae part because those relatively dry cells are of the is. And immunological properties with other mammalian lines, especially pig skin part, forming a horny layer an. According to the question `` the epidermis, called the dermis and hypodermis diet for skin. Dynamic and is nourished almost exclusively by diffused oxygen from the three…, the darker your skin down...