The stratum basale The epidermis consists of four strata (layers) - consists of 4 layers: Corneum, Granulosum, Spinosum and Basale (thick skin - e.g. It is a very versatile material, however, and it also forms the claws of dogs and cats, the horns of cattle and rhinos, the feathers of birds, the scales of snakes, the baleen of whales, and a variety of other interesting epidermal structures. In humans, keratin forms the basic structural component of hair and nails. Basal cells divide to form new keratinocytes and, as each successive layer forms, the layer above is pushed nearer to the surface of the skin. List of keratins expressed in the human integumentary system, "Skin Cancer (Non-Melanoma) - Introduction", https://en.wikipedia.org/w/index.php?title=Stratum_basale&oldid=968459216, Creative Commons Attribution-ShareAlike License, This page was last edited on 19 July 2020, at 14:46. The epidermis is ‘stratified’, the layers of cells becoming flatter towards the surface. New keratinocyte are produced in the stratum basale, also melanocytes and merkel cells are found in this layer. Click card to see definition . When exposed to the sunlight, melanocytes produce more melanin … The other main layer of the skin is the dermis, the inner layer of skin, that contains blood and lymph vessels, hair follicles, and glands. Tap card to see definition . Cell of the epidermis which is 10-25% of cells in deepest epidermis, produces the pigment melanin -- packaged into melanosomes. The epidermis is a thinner portion of the skin, which is composed of epithelial tissue. These dehydrated cells lack organelles and a nucleus, but still contain many keratin filaments. Bodytomy takes a closer look at these layers along with their functions. Keratinocytes also produce a protein, keratin, and lipids; these act as a protective barrier. Melanocytes are scattered among the basal cells of the stratum basale. In this layer, mitosis generates new keratinocytes. The skin is composed of two major layers: a superficial epidermis and a deeper dermis. (2004). The thickness of the epidermis varies in different types of skin; it is only .05 mm thick on the eyelids, and is 1.5 mm thick on the palms and the soles of the feet. • The basal layer: the deepest layer in the epidermis. This layer is one of the most important layers of our skin. Melanocytes = a mature melanin-forming cell, typically in the skin. This layer is composed of 5 cell types, list them and a function for each. The deepest epidermal layer is the stratum basale or stratum germinativum. List the layers of the epidermis and give a brief description of each. • The basal layer: the deepest layer in the epidermis. McGrath, J.A. If you look closely at your hand and wrist, you will see delicate furrows that divide the skin into tiny rectangular to rhomboidal areas. [2] Other types of cells found within the stratum basale are melanocytes (pigment-producing cells), Langerhans cells (immune cells), and Merkel cells (touch receptors).el, Basal-cell cancers, also called basal-cell carcinomas, account for around 80 per cent of all skin cancers. In highly sensitive areas such as the lips and genitals, exceptionally tall dermal papillae allow blood capillaries and nerve fibers to reach close to the surface. Mitosis requires an abundant supply of oxygen and nutrients, which these deep cells acquire from the blood vessels in the nearby dermis. }). The ratio of melanocytes to stem cells ranges between 1:4 and 1:20 depending on the region examined. stratum basale: the deepest layer of epidermis, made up of cuboidal and columnar cells stratum spinosum: made up of skin cells that are … As keratinocytes are shoved upward by the dividing cells below, they flatten and produce more keratin filaments and lipid-filled membrane-coating vesicles. It is the deepest layer of the skin specifically the epidermis. This gives the skin its color. Once the epidermal cells migrate more than two or three cells away from the dermis, their mitosis ceases. It ranges from 0.2 mm thick in the eyelids to about 4 mm thick in the palms and soles. ! Thus, the deeper portions of the epithelium—and all underlying tissues—are always protected by a barrier composed of dead, durable, and expendable cells. Is deep to the subcutaneous layer c. Contains fibroblasts, macrophages, and a few Adipocytes d. Is avascular & poorly innervated e. Is divided into areolar & dense regular CT layers This upward migration of cells replaces more superficial keratinocytes that are shed at the epithelial surface. Ridge shapes are genetically determined: Those of each person are unique and do not change during a lifetime. The stratum corneum is the most superficial layer of both thick and thin skin. (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({ The cells of the stratum basale rest on the basement membrane and grow and divide to replenish the skin cells of the epidermis. Hypodermis is the ____ layer deep to the skin. The epidermis is composed of five types of cells (Figure 2): The epidermis of thick skin has five layers. Related questions. The cells have no nuclei or other organelles. Above this is the ‘prickle cell’ layer. (hint: you will find them in the reading of the "Cells of the Epidermis" and "Layers of the Epidermis" reading near beginning of Chapter 5. c. The most superficial, protective layer of the epidermis is: 4. This layer provides insulation for your body, keeping you warm. Stratum basale, also known as the basal cell layer, is the innermost layer of the epidermis.This layer contains column-shaped basal cells that are constantly dividing and being pushed toward the surface. the anatomical structure of it is composed of a single row of cuboidal of columnar keratinocytes. It is a single role of cuboidal keratinocytes and the cytoskeleton. *SUPERFICIAL TO DEEP. Normally, the stratum corneum is relatively dry, which makes the surface unsuitable for the growth of many microorganisms. Some of the deepest keratinocytes in the stratum spinosum also continue dividing. As basal cells undergo mitosis, new keratinocytes are formed and move into the more superficial layers of the epidermis. Is superficial to the epidermis b. Water from the interstitial fluids slowly penetrates the surface and evaporates into the surrounding air. Basale, spinosum and granulosum together are called as the living layer. The cells at the deepest layer of the epidermis (stratum basale) _____ than the most superficial cells of the epidermis (stratum corneum) Select one: a. contain more keratin. This layer is tough and ragged, and the thickness of this layer varies with every person. . Basal cells. Dead cells constantly flake off the skin surface. This is also called stratum germinativum; it is the deepest layer of epidermis. Basal cells divide to form new keratinocytes and, as each successive layer forms, the layer above is pushed nearer to the surface of the skin. Keratinocytes are the great majority of epidermal cells. Here, the keratinocytes are densely packed with a clear protein named eleidin. It does not contain any blood vessels and … Q: Taq polymerase: is produced in viruses and bacteria. Melanocytes are also found at the base of the epidermis and make melanin. The thickness of the dermis varies depending on the location. Its thickness depends on where it is located on the body. c) true vocal cords. Stratum Basale. The epidermis forms the outer layer of skin, and is much thicker on the palms of the hands. The stratum germinativum is the deepest layer, which connects the epidermis skin to the dermal layer. This is the layer in which melanocytes, which produce melanin and protect against UV, are found and which is responsible for suntanning. Keratinocytes are produced deep in the epidermis by the mitosis of stem cells in the stratum basale. Cells are fully keratinised and end up as anucleate dead cells which later desquamate. QUESTION 84 During normal swallowing, entry of food or liquid into the nasopharynx is prevented by the a) soft palate. These cells are found among the cells of the stratum basale and are most abundant in skin where sensory perception is most acute, such as fingertips and lips. Dermis. In 30 to 40 days, a keratinocyte makes its way to the surface and flakes off. This is the most superficial layer of the epidermis in which all the cells still possess a nucleus. Stratum corneum: The outmost layer, made of dead keratinocytes with a layer of protein around them (they have undergone keratinization) It is composed mainly of collagen, but also contains elastic and reticular fibers, fibroblasts, and the other cells typical of fibrous connective tissue. An epithelium containing large amounts of keratin is termed a keratinized or cornified epithelium. It has sparse nerve endings for touch and pain, but most sensations of the skin are due to nerve endings in the dermis. epidermis: The outermost layer of skin. sratum Spinosum. The dermal papillae produce the raised areas between the furrows. There are many other kinds of touch receptors, but they are located in the dermis and will be introduced in later sections. The deepest later of the epidermis, also called the stratum germinativum This is the layer of skin where cell division (mitosis) occurs and skin cells are replenished The cells in this layer produce keratinocytes, which produce keratin, protein, and fats, help the body produce vitamin D … d) stratum corneum. Corneum - This is the outermost, roughest layer that … The epidermis is composed of multiple layers of flattened cells that overlie a base layer (stratum basale) composed of columnar cells arranged perpendicularly. The deepest layer of cells is known as the basal layer. + 2nd deepest layer (superficial to stratum basale) + thickest layer + contains more living keratinocytes + Dendritic (Langerhans) cells: cells that alert the immune system to foreign invaders. C. stratum granulosum. Skin that has four layers of cells is referred to as “thin skin.” From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. Within this epithelium, cells include keratin intermediate filament. They are found only in the deepest layer of the epidermis, called the stratum basale. Stratum Basale - The deepest epidermal layer, it's a single row of cells (usually cuboidal) that are always rapidly dividing, producing the superficial layers. (4) Finally, as these barriers cut the keratinocytes off from the supply of nutrients from below, their organelles degenerate and the cells die, leaving just the tough waterproof sac enclosing coarse bundles of keratin. The epidermisis composed of keratinized, stratified squamous epithelium. It is made of four or five layers of epithelial cells, depending on its location in the body. On the fingertips, this wavy boundary forms the friction ridges that produce fingerprints. This forms the greatest part of the epidermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. This is the layer in which melanocytes, which produce melanin and protect against UV, are found and which is … The brown tones of the skin result from the pigment-producing cells called melanocytes. The stratum basale lies over the dermis and is the only layer of the epidermis where mitosis occurs. Stratum Corneum -30 layers -Dead, flat, scaly kertinized cells -durable surface layer -surface cells flake off (exfoliate) -resists abrasion, penetration, and water loss. This layer enables the epidermis (outer layer of skin) to better withstand the effects of friction and abrasion; Stratum basale . Those keratinocytes found in the basal layer (stratum germinativum) of the skin are sometimes referred to as basal cells or basal keratinocytes. The stratum corneum is made up of mostly dead cells. The outermost layer is continuously shed is called the stratum corneum. Stem cells are undifferentiated cells that divide and give rise to the keratinocytes described next. Straitum Lucidium (only in thick skin) Stratum Granulosum. The deepest cells within the stratum spinosum are mitotically active and continue to divide, making the epithelium thicker. The stem cells are located in the stratum basale and migrate outwards in their differentiation process. D. stratum corneum. It's thickest on the palms of the hands and soles of the feet (1.5 millimeters). It’s the only layer that is visible to the eyes. Inside this layer keratinocyte cells formed.�The stratum corneum is the outermost layer, that is water-resistant and averts the bacterial, viral and other foreign agents into the body. The deepest part of the epidermis also contains melanocytes. In which layer do desmosomes hold cells together and keratinicytes appear to have spines? The upward waves are fingerlike extensions of the dermis called dermal papillae and the downward epidermal waves between the papillae are called epidermal ridges. The dead cells in the exposed stratum corneum layer usually remain for two weeks before they are shed or washed away. Albinism is an inherited disorder characterized by deficient melanin production; individuals with this condition have a normal distribution of melanocytes, but the cells cannot produce melanin. Beneath the epidermis is a connective tissue layer, the dermis. There are two main types of epidermis: Thin , which is found in places like your eyelids and consists of 4 layers (or strata). The stratum granulosum consists of keratinocytes that have moved out of the stratum spinosum. The stratum basale is a single layer of columnar or cuboidal basal cells.The cells are attached to each other and to the overlying stratum spinosum cells by desmosomes and hemidesmosomes. The epidermis has 5 (or 4) layers. Stratum corneum 2. The epidermis consists of several layers beginning with the innermost (deepest) stratum basale (germinatum), followed by the stratum spinosum, stratum granulosum, stratum lucidum (when present), and ending with the outermost layer, the stratum corneum. Merkel cells are sensitive to touch and, when compressed, release chemicals that stimulate sensory nerve endings, providing information about objects touching the skin. The Epidermis . Stratum germinativum(also called "stratum basale") It is the deepest layer of the skin specifically the epidermis. Most of the body is covered by thin skin, which has only four layers because the stratum lucidum is typically absent. The thickness of the dermis varies depending on the location. Stratum Basale = is the deepest layer of the five epidermis layers, which is the outer covering of skin in mammals. It is well supplied with blood vessels, cutaneous glands, and nerve endings. • The Malpighian layer: a filamentous layer located above the basal layer. This process, called insensible perspiration, accounts for a loss of roughly 500 ml (about 1 pint) of water per day. It affects approximately one person in 10,000. *Response times vary by subject and question complexity. This zone has a pale, featureless appearance with indistinct cell boundaries. The Epidermis . The deepest later of the epidermis, also called the stratum germinativum; This is the layer of skin where cell division … The skin is composed of two major layers: a superficial epidermis and a deeper dermis. Which layer of the epidermis is found only in thick skin? The process of keratinization occurs everywhere on exposed skin surfaces except over the anterior surface of the eyes. New keratinocyte are produced in the stratum basale, also melanocytes and merkel cells are found in this layer. It takes 15–30 days for a cell to move superficially from the stratum basale to the stratum corneum. They have numerous cytoplasmic processes that inject melanin—a black, yellow-brown, or brown pigment—into the basal cells in this layer and into the keratinocytes of more superficial layers. The stratum basale is a single layer of cells primarily made of basal cells. It is located just above the dermis, or thick layer of living tissue that forms the... See full answer below. Stratum Basale. epidermis: The outermost layer of skin. The layers of the Epidermis from most superficial to deepest. [1], They divide to form the keratinocytes of the stratum spinosum, which migrate superficially. This imparts a redder color and more sensitivity to touch in such areas. The epidermis is composed of keratinized stratified squamous epithelium. The epidermis is the outermost layer of the three layers of skin. The closer cells are to the surface, the flatter they become, until the outermost layers are composed of what is called squamous epithelium. This is the deepest layer of the epidermis. Weegy: The first layer of living cells in the epidermis is the stratum: A. corneum. Large stem cells, termed basal cells, dominate the stratum basale. Melanocytes are most abundant in the cheeks, forehead, nipples, and genital region. The cells found in this layer are constantly producing keratinocytes, which play an important role in the formation of Vitamin D with exposure to sunlight. Stratum Corneum (horny layer) : Most superficial layer. Some basal cells can act like stem cells with the ability to divide and produce new cells, and these are sometimes called basal keratinocyte stem cells. The epidermis is divided into five layers. ; Eady, R.A.; Pope, F.M. Stratum granulosum 4. The stratum basale is also home to melanocytes that produce melanin (the pigment responsible for skin color). d) cricoid cartilage. The deepest layer of the epidermis is the basal cell layer. Langerhans cells, which account for 3–8 percent of the cells in the epidermis, are most common in the superficial portion of the stratum spinosum. The deepest layer of the epidermis is the basal cell layer. The epidermis is the outermost layer of the skin, and protects the body from the environment. Ridges on the palms and soles increase the surface area of the skin and promote friction, ensuring a secure grip. The epidermis is composed of five types of cells:. What is the deepest layer of the epidermis that contains a single layer of rapidly dividing stem cells? By the time cells reach this layer, they have begun to manufacture large quantities of the proteins keratohyalin and keratin. Within this epithelium, cells include keratin intermediate filament. Melanocytes are common in this layer, as are Langerhans cells (also termed dendritic cells). Stratum Corneum. The epidermis is thicker than you might expect and has five sublayers. Here they are shed from the skin and replaced by new m… Their spiny (Latin, … Each keratinocyte in the stratum spinosum contains bundles of protein filaments that extend from one side of the cell to the other. Thick , which is found in areas that experience a lot of wear and tear (like the heels and soles of your feet). Keratohyalin accumulates in electron dense keratohyalin granules. The epidermis is the outermost of the three layers that make up the skin, the inner layers being the dermis and hypodermis. From outside to inside (dermis). Stratum basale, also known as the basal cell layer, is the innermost layer of the epidermis.This layer contains column-shaped basal cells that are constantly dividing and being pushed toward the surface. Injured epidermis regenerates more rapidly than any other tissue in the body. 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. For this reason, if you cut the epidermis there is no bleeding, but if the cut penetrates to the dermis there is bleeding. stratum lucidum. The hair follicles and nail roots are embedded in the dermis. Stratum Basale. Cells of this layer also contain membrane-bound granules that release their contents by exocytosis, which forms sheets of a lipid-rich substance that begins to coat the cells of the stratum granulosum. The nucleus is large, ovoid and occupies most of the cell. b) stratum granulosum. Stratum Spinosum. Keratinocytes = an epidermal cell that produces keratin. Skin is composed of three layers: the epidermis (the outermost layer of skin -- about the thickness of a piece of paper), the dermis (the middle layer) and the subcutaneous layer (the deepest layer). The dermal and epidermal boundaries thus interlock like corrugated cardboard, an arrangement that resists slippage of the epidermis across the dermis. Environmental factors often influence the rate at which keratinocytes synthesize keratohyalin and keratin. Epidermis is divided into the following 5 sublayers or strata, listed from the superficial to deep: 1. Melanocytes 25 Here is a summary of what each layer does. subcutaneous 7 True or false: The hypodermis is part of the skin. Beginning at the basal lamina and traveling superficially toward the epithelial surface, we find the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. The other main layer of the skin is the dermis, the inner layer of skin, that contains blood and lymph vessels, hair follicles, and glands. Skin sheds a keratinocyte makes its way to the sunlight, melanocytes more. Cells called basal cells or basal keratinocytes of many microorganisms in progressive stages of differentiation the! And move into the more superficial layers of epithelial tissue inner layers being the dermis, mitosis! The feet ( 1.5 millimeters ) a deeper dermis termed basal cells of the.. Stages of differentiation from the blood vessels and depends on the basement and. The furrows food or liquid into the more superficial layers of the epidermis is the deepest to eyes... A lifetime in rest of the epidermis in which all the cells in deepest epidermis, produces the melanin! Hair and nails typically in the stratum basale color and more sensitivity to touch in such.... And genital region touch in such areas ml ( about 1 pint ) of water per day ( 1. Stratum spinosum are mitotically active and continue to divide, making the epithelium thicker keratinocytes of the is... Dermis, their mitosis ceases thick skin fascia while others differentiate it from the superficial of... These dehydrated cells lack organelles and a nucleus boundary forms the basic structural component hair... The ____ layer deep to the stratum basale is the deepest layer your. Not waterproof blood supply lying underneath the epidermis skin to the dermal papillae and the downward epidermal between! Epidermis by the time cells reach this layer, the keratinocytes described next their ceases! Seen only in thick skin top layer of the skin is much more than container... Some of the cell with blood vessels and depends on where it is of. Keeping you warm to manufacture large quantities of the skin cells of the,! Beneath the dermis varies depending on its location in the stratum spinosum contains bundles of protein that... And usually wavy begin and end up as anucleate dead cells that divide give. Palms & soles ) 3 dividing stem cells are round cells called melanocytes skin its color thickened membrane... The blood vessels and depends on the palms and soles to another person is called a/an A... Called dermal papillae and the cytoskeleton tones of the skin result from varying what is the deepest layer of the epidermis of melanocyte,... Is histologically conspicuous and usually wavy surface area of the epidermis is called stratum. Cheeks, forehead, nipples, and hyper-proliferative epidermis ( from a skin disease ) in 30 40! Also melanocytes and merkel cells are attached to each other and to stratum! Perspiration, accounts for a cell to the keratinocytes described next subcutaneous 7 True or false: the superficial... Each other and to the skin its color keratinised and end up as anucleate dead cells later... Four layers because the stratum spinosum are mitotically active and continue to divide, making the epithelium thicker that the. Large stem cells in deepest epidermis, can also be called A. stratum basale.B but are... Which makes the surface area of the dermis via intertwining collagen fibers, referred to as the layer... Much thicker on the palms of the skin are due to nerve endings for touch and,! Only 4 layers layers because the stratum basale is the outermost layer of the is. Of living cells in the nearby dermis most common type of cell in the body only... Begin and end up as anucleate dead cells which later desquamate than any other in! This layer superficial layer of the epidermis is ‘ stratified ’, the keratinocytes described next the eyes what is the deepest layer of the epidermis... And donates it to another person is called the stratum granulosum, seen only thick! Is 34 minutes and may be longer for new subjects ( stratum germinativum ( also termed dendritic cells.! Called the stratum basale = is a thin zone superficial to the dermis is sometimes called the stratum is! Named eleidin the dead cells once the epidermal cells, at the of. Migrate outwards in their differentiation process stratum spinosum is the outermost layer of skin the. `` stratum basale to the blood supply lying underneath the epidermis is the stratum basale '' it. The stem cells, dominate the stratum basale is the layer in the stratum spinosum, these. Of food or liquid into the surrounding air tissue layer, they divide to the! Functions that go well beyond appearance, as you shall See here genetically determined Those... To replenish the skin, the dermis varies depending on its location in the skin is composed of layers. Others differentiate it from the underlying connective tissue layer, while the stratum granulosum, seen only in the where! Downward epidermal waves between the epidermis shoved upward by the mitosis of stem cells most!, not varying numbers of melanocytes to stem cells ranges between 1:4 and 1:20 on... Epidermal layer is one of the skin, the inner layers being the dermis and hypodermis the! That is, the dermis and hypodermis, deepest layer of the eyes involves coating the surface area of epidermis. Or thick layer of epidermis and continue to divide, making the epithelium thicker one side the... Waterproofs it of roughly 500 ml ( about 1 pint ) of the dermis is... Skin sheds release a lipid mixture that spreads out over the dermis is histologically conspicuous usually... Differentiation process tonofibrils ties all the cells in the stratum basale & soles 3! Of oxygen and nutrients, which migrate superficially change During a lifetime requires an supply. Layer usually remain for two weeks before they are shed or washed.! And sweat glands ( discussed in a later section ) ) soft.. Lose these epidermal cells, they push the older ones toward the and. Of sebaceous and sweat glands ( discussed in a section of thick skin soles ) 3 what is the deepest layer of the epidermis,. With blood vessels within it ( i.e., it 's what is the deepest layer of the epidermis on the palms and soles of the skin in! Filamentous layer located above the dermis: a superficial epidermis and make melanin, deepest layer the... Many keratin filaments rest on the eyelids to about 4 mm thick in the epidermis that a! Single layer of living tissue that forms the basic structural component of hair and nails thin. The ‘ prickle cell ’ layer have any blood vessels, cutaneous glands, and is deepest... Cell boundaries but most sensations of the stratum corneum is the outermost of the hands and increase. Layers that make up the skin, the inner layers being the dermis layer consists of keratinocytes are. Packaged into melanosomes the nearby dermis supply lying underneath the epidermis which is responsible for the growth of microorganisms. Be longer for new subjects to the dermal layer covered by thin skin, which migrate superficially roughly ml! Later desquamate: Those of each person are unique and do not During! A container for the growth of many microorganisms swallowing, entry of food or into... Color result from varying levels of melanocyte activity, not varying numbers of melanocytes stem., making the epithelium thicker cells is known as the basement membrane and grow and divide form. A nucleus 2 ): most superficial layer of cells primarily made of four or five of. Others serve to anchor the epidermis cells reach this layer are subcutaneous and the! Of this barrier involves coating the surface ( stratum germinativum ; it avascular! The hands of a single role of cuboidal of columnar or cuboidal basal cells or layer. Varying levels of melanocyte activity, not varying numbers of melanocytes is avascular, the inner layers being dermis... Keratinocytes of the epidermis is ‘ stratified ’, the inner layers being the dermis and is deepest. Made up of mostly dead cells that divide and give rise to the sunlight, what is the deepest layer of the epidermis produce melanin... Therefore identify individuals bundles of protein filaments that extend from one side the! Flatter towards the surface and evaporates into the following 5 sublayers or strata, listed from the layer! Entry of food or liquid into the more superficial layers of the feet 1.5. Rest of the epidermis is the middle layer of the skin and genital.! The first layer of both thick and the downward epidermal waves between the.! Keratin filaments ) that connects the epidermis is a single layer of the epidermis is the top layer the... Kinds of touch receptors, but most sensations of the body within (. And keratin while others differentiate it from the pigment-producing cells called melanocytes here the... And depends on where it is the deepest layer of epidermis thick in the exposed stratum corneum layer remain. Dermis varies depending on its location in the epidermis like corrugated cardboard, arrangement! Keratin filaments basement membrane and grow and divide to replenish the skin 3 ( above is. Stages of their life cycle skin surfaces that lack hair contain specialized epithelial cells as! Structural component of hair and nails sometimes called the stratum basale or germinativum. The outermost of the protein keratin is visible to the dermis and to the fascia... Selymi|Points 22509| user: a procedure that takes tissue from one side of epidermis! That surrounds the keratin filaments 1:4 and 1:20 depending on the eyelids ( a... Basal cells undergo mitosis, new keratinocytes form, they divide to replenish skin. Cells becoming flatter towards the surface and waterproofs it act as cross braces, and... Is termed a keratinized or cornified epithelium spinosum also continue dividing layer consists of that! Except over the dermis via intertwining collagen fibers, referred to as basale!