Stratum Granulosum

The stratum granulosum consists of two to five layers of flat keratinocytes—more in thick skin than in thin skin. These keratinocytes contain coarse, dark-staining kerato-hyalin granules that give this layer its name. These granules consist of a protein that combines with intermediate filaments of the cytoskeleton and converts them to keratin. Keratinocytes in the stratum spinosum and stratum granulosum also produce lipid-filled membrane-coating vesicles. Here in the stratum granulosum, these vesicles undergo exocytosis and release a glycolipid that spreads out over the keratinocyte membranes and waterproofs the skin. The glycolipid also constitutes a barrier between the surface cells of the skin and the deeper layers. Cut off from their nutrient supply, cells above the stratum granulosum quickly die.

Saladin: Anatomy & I 6. The Integumentary I Text I I © The McGraw-Hill

Physiology: The Unity of System Companies, 2003 Form and Function, Third Edition

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