Stratum granulosum

The stratum granulosum (or granular layer) is a thin layer of cells in the epidermis.[1] Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer. These cells contain keratohyalin granules, which are filled with histidine- and cysteine-rich proteins that appear to bind the keratin filaments together. Therefore, the main function of keratohyalin granules is to bind intermediate keratin filaments together.[2][3]

Histologic image showing a section of epidermis. Stratum granulosum labeled near center.

At the transition between this layer and the stratum corneum, cells secrete lamellar bodies (containing lipids and proteins) into the extracellular space. This results in the formation of the hydrophobic lipid envelope responsible for the skin's barrier properties. Concomitantly, cells lose their nuclei and organelles causing the granular cells to become non-viable corneocytes in the stratum corneum.[3]

Additional images
  • Epidermis and dermis of human skin
  • Section of epidermis

See also

References
  1. James, William; Berger, Timothy; Elston, Dirk (2005) Andrews' Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. Page 2. ISBN 0-7216-2921-0.
  2. Marks, James G; Miller, Jeffery (2006). Lookingbill and Marks' Principles of Dermatology (4th ed.). Elsevier Inc. Page 7. ISBN 1-4160-3185-5.
  3. Ovaere P; Lippens S; Vandenabeele P; Declercq W. (2009). "The emerging roles of serine protease cascades in the epidermis". Trends in Biochemical Sciences. 34 (9): 453–463. doi:10.1016/j.tibs.2009.08.001. PMID 19726197.
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