Stratum lucidum where is it found

The most superficial layer of the skin is the epidermis which is attached to the deeper dermis. Accessory structures, hair, glands, and nails, are found associated with the skin. The deeper layer of skin is well vascularized has numerous blood vessels and is superficial to the hypodermics.

It also has numerous sensory, and autonomic and sympathetic nerve fibers ensuring communication to and from the brain. View this animation to learn more about layers of the skin.

The skin consists of two main layers and a closely associated layer. What are the basic functions of each of these layers? The epidermis is composed of keratinized, stratified squamous epithelium.

It is made of four or five layers of epithelial cells, depending on its location in the body. It does not have any blood vessels within it i. Most of the skin can be classified as thin skin. It has a fifth layer, called the stratum lucidum, located between the stratum corneum and the stratum granulosum Figure 5.

A keratinocyte is a cell that manufactures and stores the protein keratin. Keratin is an intracellular fibrous protein that gives hair, nails, and skin their hardness, strength, and water-resistant properties. The keratinocytes in the stratum corneum are dead and regularly slough away, being replaced by cells from the deeper layers Figure 5. The stratum basale also called the stratum germinativum is the deepest epidermal layer and attaches the epidermis to the basal lamina, below which lie the layers of the dermis.

The cells in the stratum basale bond to the dermis via intertwining collagen fibers, referred to as the basement membrane. Dermal papillae increase the strength of the connection between the epidermis and dermis; the greater the folding, the stronger the connections made Figure 5. The stratum basale is a single layer of cells primarily made of basal cells. A basal cell is a cuboidal-shaped stem cell that is a precursor of the keratinocytes of the epidermis.

All of the keratinocytes are produced from this single layer of cells, which are constantly going through mitosis to produce new cells. As new cells are formed, the existing cells are pushed superficially away from the stratum basale. Two other cell types are found dispersed among the basal cells in the stratum basale. The first is a Merkel cell , which functions as a receptor and is responsible for stimulating sensory nerves that the brain perceives as touch.

These cells are especially abundant on the surfaces of the hands and feet. The second is a melanocyte , a cell that produces the pigment melanin. Melanin gives hair and skin its color, and also helps protect the DNA in the nuclei of living cells of the epidermis from ultraviolet UV radiation damage.

As the name suggests, the stratum spinosum is spiny in appearance due to the protruding cell processes that join the cells via a structure called a desmosome. The desmosomes interlock with each other and strengthen the bond between the cells. Unstained epidermis samples do not exhibit this characteristic appearance. The stratum spinosum is composed of eight to 10 layers of keratinocytes, formed as a result of cell division in the stratum basale Figure 5.

Interspersed among the keratinocytes of this layer is a type of dendritic cell called the Langerhans cell , which functions as a macrophage by engulfing bacteria, foreign particles, and damaged cells that occur in this layer. If you zoom on the cells at the outermost layer of this section of skin, what do you notice about the cells?

The keratinocytes in the stratum spinosum begin the synthesis of keratin and release a water-repelling glycolipid that helps prevent water loss from the body, making the skin relatively waterproof.

As new keratinocytes are produced atop the stratum basale, the keratinocytes of the stratum spinosum are pushed into the stratum granulosum. The stratum granulosum has a grainy appearance due to further changes to the keratinocytes as they are pushed from the stratum spinosum. The cells three to five layers deep become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin , which is fibrous, and keratohyalin , which accumulates as lamellar granules within the cells see Figure 5.

These two proteins make up the bulk of the keratinocyte mass in the stratum granulosum and give the layer its grainy appearance. The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes that will form the stratum lucidum, and the stratum corneum.

A similar process of producing cells packed with keratin occurs in the accessory structures of hair and nails. The stratum lucidum is a smooth, seemingly translucent layer of the epidermis located just above the stratum granulosum and below the stratum corneum. It is readily visible by light microscopy in areas of thick skin, which are formed on the palms of the hands and soles of the feet.

However in the rest of the body where the skin is thinner this stratum does not appear differentiated from the granular region.

The stratum lucidum layer is composed of three to five layers of dead flattened keratinocytes. These cells do not show distinct boundaries and are filled with eleidin, an intermediate form of keratin.

They are surrounded by an oily substance. The thickness of the stratum lucidum is controlled by the rate of mitosis of the epidermal cells. The stratum lucidum is responsible for the capability of the skin to stretch. Synonym s :. New Zealand is known for its unique biodiversity, caused by its remarkable geography and geologic history. Breaking away.. The arthropods were assumed to be the first taxon of species to possess jointed limbs and exoskeleton, exhibit more adva..

This tutorial describes the independent assortment of chromosomes and crossing over as important events in meiosis. Nutrients in the soil are essential to the proper growth of a land plant. This tutorial deals with the properties of soi.. The epidermal layer of the skin and digestive tract are the two tissues that are directly exposed to the outside world, and therefore are most vulnerable to its damaging effects.

In both, there is constant proliferation of cells in the bottom layer stratum basale which constantly move up to the top where they are lost. This means damaged cells are continually shed, and replaced with new cells.

Find out more about the four different types of cell found in the epidermis. The basal cell layer stratum basale , or stratum germinosum , is a single layer of cells, closest to the dermis. It is usually only in this layer that cells divide. Some of the dividing cells move up to the next layer.