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
Was this article helpful?
This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.