Stratum granulosum
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| Stratum granulosum | |
|---|---|
 | |
| Section of epidermis. (Stratum granulosum labeled at left, third from top.) | |
| Latin | stratum granulosum epidermidis |
| Gray's | subject #234 1064 |
| Dorlands/Elsevier | s_25/12761233 |
In microscopic views of skin, the stratum granulosum layer of the epidermis lies between the stratum spinosum, below, and the stratum 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.
The stratum granulosum layer typically contains 1 to 3 rows of squamous cells with many small basophilic 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.[1][1]
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.
This layer also includes lamellar granules and tonofibrils.
References
External links
- Histology at BU 08422loa - "Integument: thick skin"
Integumentary system | |||||||||
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| Skin layers | cutis: Epidermis (Stratum corneum, Stratum lucidum, Stratum granulosum, Stratum spinosum, Stratum germinativum/basale) • Dermis Subcutaneous tissue | ||||||||
| Skin appendages |
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Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
