Structure of Skin by Aseem
Download as PPTX, PDF31 likes4,720 views
The document discusses the structure and embryology of the skin, detailing its various layers, types, and components including the epidermis, dermis, and hypodermis. It outlines the skin's developmental timeline and the cellular structure involved, emphasizing the roles of different skin appendages and connective tissues. Additionally, it highlights the properties and functions of collagen and elastic fibers within the dermis.
Structure of Skin by Aseem
- 1. STRUCTURE OF SKIN Dr Aseem Sharma Dermatology Resident
- 2. INTRODUCTION • Surface Area 1.62/ 1.45 sq metres (M/F) • 16 – 20% Body Weight (approx 5 kg) • Largest Organ
- 3. TYPES OF SKIN • 02 Types : GLABROUS (Non-Hairy) ‘Dermatolglyphics’ NON-GLABROUS (Hair-bearing)
- 4. LAYERS OF THE SKIN EPIDERMIS CUTICLE/EPITHELIUM DERMIS HYPODERMIS/PANNICULUS ADIPOSUS - SUBCUTIS
- 6. APPENDAGES OF THE SKIN • Hair • Nails • Glands 1. Eccrine 2. Apocrine 3. Sebaceous
- 7. EMBRYOLOGY SPECIFICATION : Commitment 0-2 months FL MORPHOGENESIS: Specialization 2-5 months FL DIFFERENTIATION: Maturation 5-9 months FL
- 8. EMBRYOLOGICAL ORIGINS ECTODERMAL : Epidermis, Pilosebaceous Unit, Eccrine Gland, Nail NEURO-ECTODERMAL : Melanocytes, Nerves, Sensory Receptors MESODERMAL : Dermis, Hypodermis, Muscle, Adipocytes, Blood Vessels, Mast Cells, Langerhan’s cells, Macrophages
- 9. EMBRYOLOGY • EPIDERMIS (ECTODERMAL) 3rd Week FL - Single layer 6th Week FL - Periderm + Germinative Layer 10th Week FL - Hemi-Desmosomal/Desmosomal Protein 11th Week FL - Intermediate Layer 12-16th Week - Microvilli 20th Week - KERATOHYALINE granules in Intermedicate Layer, Germinative Layer proliferation, Epidermal Cornification 24th Week - Vernix Caseosa shed; Keratinization done
- 10. EMBRYOLOGY • DERMIS (MESENCHYME) 4TH Week FL - Collagen Fibres 6th Week FL - Touch Pads (Extremities) 8 – 14th Week FL - Melanoblasts, Phagocytes 14 – 22nd Week FL - Fibroblasts, Merkel, Mast Cells 22nd Week FL – Elastin Fibres
- 11. EMBRYOLOGY • HYPODERMIS (MESENCHYME) 14 Weeks FL - Lipoblasts Lipocytes
- 12. EPIDERMIS • Stratified Squamous Epithelium • Variable Thickness 0.4 – 1.5 mm • Cellular Components : 95% Keratinocytes 5% Merkel, Melanocytes, Langerhans
- 14. 8/5/2013 14 STRATUM BASALE • Stratum Germinativum • Small, Continuous, Cuboidal, 1-cell thick, Nucleated • Dense cytoplasm, Dark staining Nuclei; Cell division q 18-19 days • Transient amplifying cells Post-Mitotic cells Epidermal stem cells
- 15. STRATUM SPINOSUM • Prickle-Cell layer • Desmosomes Spines • 8-10 cell layers, Nucleated • Large, Flattened, Polyhedral cells
- 16. 8/5/2013 16 STRATUM GRANULOSUM • Intracellular Basophilic Keratohyaline granules • 2-5 cell layer, Nucleated • Odland Bodies/ Lamellar Granules – facilitate desquamation
- 17. 8/5/2013 17 STRATUM LUCIDUM • Glabrous Skin only • ‘Electron-Luscent’ • Nucleated, Transitional Cells
- 18. STRATUM CORNEUM • Outermost Skin Layer • 20-25 Cell layer • Corneocytes - Enucleated, minus Cytoplasmic Organelles, Terminally Differentiated; ‘Soft Keratin’
- 19. DERMIS • 10-40 X thicker than Epidermis • Variable thickness 1-5 mm • Fibrous, Filamentous, Amorphous Connective Tissue with Nerves, Vessels and embedded in Ground Substance • Restructuring/ Remodelling • Pliablility, Elasticity, Tensile Strength
- 21. PAPILLARY DERMIS • 1/10th of Dermis; Interdigitates with Epidermal Rete Ridges. • Small Diameter COLLAGEN Fibres • OXYTALAN ELASTIC Fibres • Higher Metabolic Rate; Loose Connective tissue
- 22. RETICULAR DERMIS • 9/10th of Dermis; Merges with Underlying Subcutaneous Fat • Large Diameter COLLAGEN Fibres • ELAUNIN ELASTIC Fibres • Densely-packed Connective Tissue
- 23. COMPONENTS OF DERMIS ACELLULAR (MAJOR COMP) GROUND MATRIX CONNECTIVE TISSUE MATRIX (Collagen/Elastin) CELLULAR FIBROBLASTS MACROPHAGES/MONOCYTES/DENDROCYTES MAST CELLS
- 24. GROUND SUBSTANCE • Amorphous, supporting Matrix • Proteoglycans & Glycosaminoglycans • 0.2 % of the dry weight of Dermis; can bind up water upto 1000 times its volume • Binds Growth Factors
- 25. GROUND SUBSTANCE PGs Chondroitin Sulfates Dermatan Sulfates Heparan Sulfates GAGs Hyaluronan
- 26. COLLAGEN • Soft, Flexible BUT Strong, Inelastic • 75% of dry weight of DERMIS Type I 80-90% Dermis Type II 8-10% Dermis Type III Papillary Dermis Type IV Basement Membrane Type V < 5% Dermis Type VI Inter-Fibrillar Spaces Type VII Anchor Fibrils in DEJ
- 27. ULTRASTRUCTURE COLLAGEN • Triple Helical Conformation • (Glycine-X-Y) X - Proline Y - Hydroxyproline Glycosylated Interchain Bonding Secreted Cleaved Cross-Linked
- 28. 8/5/2013 28 ELASTIC FIBRES • 4% of dry weight of Dermis • Impart the property to regain original shape after deforming forces are removed • Maintain normal Skin Configuration • Elastogenesis by Microfibril deposition
- 29. HYPODERMIS • PANNICULUS ADIPOSUS/ SUBCUTIS • Insulating layer of Adipocytes
- 30. THANK YOU