Answer
a. * Stratum corneum- consists of up to 30 layers of dead, scaly, keratinized cells that form a durable surface layer. It is especially resistant to abrasion, penetration, and water loss.
b. * Stratum lucidum (absent)- thin zone superficial to the stratum granulosum, seen only in thick skin. Here, the keratinocytes are densely packed with a clear protein named eleidin
c. * Stratum granulosum-consists of three to five layers of flat keratinocytes—more in thick skin than in thin skin. Th keratinocytes of this layer contain coarse, dark-staining keratohyalin granules that give the layer its name.
d. * Stratum spinosum consists of several layers of keratinocytes. In most skin, this is the thickest stratum, but in thick skin it is usually exceeded by the stratum corneum. For reasons you will see in reading about the keratinocyte life history, cells of the stratum spinosum appear flatter and flatter the higher you look in this layer. Dendritic cells are also found throughout the stratum spinosum, but are not usually identifiable in routinely stained tissue sections.
e. * Stratum Basale -consists mainly of a single layer of cuboidal to low columnar stem cells and keratinocytes resting on the basement membrane. Scattered among these are the melanocytes, tactile cells, and stem cells. As the stem cells divide, they give rise to keratinocytes that migrate toward the skin surface and replace lost epidermal cells.
Work Step by Step
Layers of the Epidermis PG 179
