Question

Describe various layers of epidermis found in Man.

Answer 1

• The human skin is made up of 2 layers Epidermis and dermis. The epidermis is the uppermost layer and dermis is the lower layer.
• The epidermis is made up of keratinized stratified squamous epithelium. and has 4 main principle type of cell ie keratinocytes, melanocytes, Langerhans cells, and Merkel cells.
• Keratinocytes produce keratin protein, Melanocytes produce the melanin pigments, Langerhans cells are present in the skin for immune response and marker cells are for the function of a sensation of touch.
  
• The epidermis is made up of 5 other layers, from deep to superficial are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidium, and stratum corneum.
• In most regions of the body, the epidermis has 4 strata or layers ie the basal, spinosum, granulosum and a thin corneum. While the skin on palms, fingertips, and soles have a layer of lucidium above granulosum and a thick layer of corneum.
  

Structure of the layers of the epidermis is as follows.

• Stratum basale-- Deepest layer which is composed of a single row of cuboidal keratinocytes. Stem cells of this layer divide to form new cells and provide keratinocytes, melanocytes to the other layers.
• Stratum spinosum- Made up to 8 to 10 rows of keratinocytes with the bundle of tonofilaments.
• Stratum granulosum-This layer has 3 to 5 rows of flattened keratinocytes in which organelles have started to degrade and they release lipid-rich, water repellent secretion.
• Stratum lucidium-Present only in a skin offingertipss, palms, and soles. It consists of 3 to 5 layers of clear, flat, dead keratinocytes with a large amount of keratin.