File:Epidermis cartoon 01.jpg: Difference between revisions

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General structure of the Adult Epidermis

This cartoon shows keratinocyte differentiation (cornification) within overall structure of the skin epithelium. In addition, the cellular junctions are also indicated.

stratum basale - (basal layer) keratinocytes proliferate by mitosis. This layer also contains the stem cell population.
stratum spinosum - keratinocytes reinforce their cytoskeletal keratin filament network and adjacent cells interact through desmosomes.
stratum granulosum - keratinocytes become more flattened and express proteins that aggregate to form keratohyalin granules. Lipids are also produced and stored in lamellar bodies.
stratum corneum - keratinocytes lose their organelles, including the nucleus, and become the dead, flattened corneocytes.

Reference

J Cell Biol. 2008 February 11; 180(3): 451–458. doi: 10.1083/jcb.200709098.

Copyright

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http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2234247&rendertype=figure&id=fig1

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current	14:30, 17 May 2012		545 × 375 (96 KB)	Z8600021 (talk \| contribs)	==General structure of the Adult Epidermis== Introduction excerpt: :"The basal layer, or stratum basale, of the epidermis contains proliferating keratinocytes (Fig. 1). Upon withdrawal from the cell cycle, these basal keratinocytes detach from the basem

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Foundations - Histology Epithelia and Skin

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 ==General structure of the Adult Epidermis==
-This cartoon shows keratinocyte differentiation within overall structure of the skin epithelium. In addition, the cellular junctions are also indicated.
+This cartoon shows keratinocyte differentiation (cornification) within overall structure of the skin epithelium. In addition, the cellular junctions are also indicated.
+# '''stratum basale''' - (basal layer) keratinocytes proliferate by mitosis. This layer also contains the stem cell population.
+# '''stratum spinosum''' - keratinocytes reinforce their cytoskeletal keratin filament network and adjacent cells interact through desmosomes.
-* stratum basal - (basal layer) of the epidermis contains proliferating keratinocytes
+# '''stratum granulosum''' - keratinocytes become more flattened and express proteins that aggregate to form keratohyalin granules. Lipids are also produced and stored in lamellar bodies.
+# '''stratum corneum''' - keratinocytes lose their organelles, including the nucleus, and become the dead, flattened corneocytes.
-Upon withdrawal from the cell cycle, these basal keratinocytes detach from the basement membrane and undergo a terminal differentiation program to become corneocytes in the outer layers of the epidermis. This process is called cornification. In the intermediate stratum spinosum, the cells reinforce their cytoskeletal keratin filament network, and adjacent cells interact via many desmosomes, a specialized type of cell junction, to resist physical trauma. In the stratum granulosum, the keratinocytes become more flattened and express certain proteins such as profilaggrin and loricrin, which aggregate to form the typical keratohyalin granules of the stratum granulosum. In addition, lipids are produced and stored in lamellar bodies. At the final stage of differentiation, the keratinocytes lose their organelles, including the nucleus, and become the dead, flattened corneocytes of the stratum corneum. During cornification, proteins are cross-linked at the inner side of the cytoplasmic membrane to form a cornified envelope (for review see Candi et al., 2005). In the transitional layer between the stratum granulosum and the stratum corneum, lipids are extruded to form a water-repelling envelope around the cornified envelope, thereby assuring an adequate permeability barrier function of the mammalian epidermis. Improper formation of these envelopes results in an impaired epidermal barrier that cannot protect against dehydration, UVB, and infection. Finally, corneocytes are shed from the skin by a process called desquamation."
-Caspase-14 reveals its secrets.
-Denecker G, Ovaere P, Vandenabeele P, Declercq W.
-J Cell Biol. 2008 Feb 11;180(3):451-8. Epub 2008 Feb 4. Review.
-PMID: 18250198
 ===Reference===