- Stratum granulosum
Infobox Anatomy
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Latin = stratum granulosum epidermidis
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Caption = Section of epidermis. (Stratum granulosum labeled at left, third from top.)
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DorlandsPre = s_25
DorlandsSuf = 12761233
Inmicroscopic views ofskin , the stratum granulosum layer of the epidermis lies between thestratum spinosum , below, and thestratum lucidum , above, in stratified squamous keratinized thick skin of palms and soles. Thin skin, which covers the rest of the body, lacks a definite stratum lucidum and stratum granulosum.This is the highest layer in the epidermis where living cells are found; the stratum lucidum above appears clear due to auto-digestion of cellular organelles.
Granules
The stratum granulosum layer typically contains 1 to 3 rows of
squamous cells with many smallbasophilic granules in their cytoplasm.These prominent keratohyalin granules are not membrane-bound. Keratin bundles pass through the granules, which contain a phosphorylated histidine-rich protein and other cystine-rich proteins. The cells in the stratum granulosum contain also large amounts of
filaggrin , a protein thought to serve in bundling keratin. Membrane-coated lamellar granules (0.1 to 0.3 micrometers) are also present and contain lipids. The lamellar granules are exocytosed in this layer to generate a waterproof barrier. This waterproofing also prevents life-sustaining nutrient transport, and thus leads to the characteristic cell death of the outer layers of keratinized epithelium. [L.P. Gartner and J.L. Hiatt, Color Textbook of Histology, 3rd ed., Elsevier, 2007, p 331-336.] [Junqueria and Carneiro, Basic Histology Text & Atlas, 11th ed., McGraw-Hill, 2005, p 361.]This layer also includes lamellar granules and tonofibrils.
ee also
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Hypergranulosis References
External links
* - "Integument: thick skin"
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