INTEGUMENT Dr. Larry Johnson Objectives Distinguish between the 5 layers of epidermal cells in thick skin and the differences in these found in thin skin. Describe the organization of the two layers comprising the dermis. Detail the structure of the sebaceous gland, eccrine sweat gland, and aprocrine sweat gland. Recognize melanin and its functional significance. From: Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory Manual BINARY ORIGIN OF SKIN EPIDERMIS ECTODERM 31 BINARY ORIGIN OF SKIN EPIDERMIS ECTODERM DERMIS - MESODERM 31 Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION RECEIVES STIMULI TEMPERATURE PAIN PRESSURE Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION RECEIVES STIMULI TEMPERATURE PAIN PRESSURE BASIS OF RECOGNITION AND YIELDS CLUES TO ONES WELL BEING Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION RECEIVES STIMULI TEMPERATURE PAIN PRESSURE BASIS OF RECOGNITION AND YIELDS CLUES TO ONES WELL BEING FAT METABOLISM IN THE SUBCUTANEOUS LAYER Integument CHARACTERISTICTHICK SKINTHIN SKIN Surface TextureAlternating ridges and grooves Smooth Epidermis/Dermis Interface Interdigitating ridgesLess prominent ridges Epidermal StrataS. Basale S. Spinosum S. Granulosum S. Lucidum S. Corneum Same as thick skin, except: no S. Lucideum. The corneum, granulosum, and spinosum layers are reduced in thickness. Hairs and Sebaceous Glands NoneRegionally variable Sweat GlandsAbundantModerate REGIONAL VARIATION OF THE EPIDERMIS THICK SKIN - SOLE OF FOOT (1.4 mm THICK) THIN SKIN - EYELID AND MOST OF BODY (0.07 TO 0.12 mm) CORNEA OF EYE - TRANSPARENT APPENDAGES - HAIR FOLLICLES NAILS GLANDS REGIONAL VARIATION OF THE EPIDERMIS Slide 29: Slide 29: Thick Skin (ventral surface of finger) Epiderm is ) Dermis Hypodermis Adipocytes Copyright McGraw-Hill Companies Slide 29: Slide 29: Thick Skin (ventral surface of finger) Papillary layer Reticular layer Dermal papillae Epidermal peg Copyright McGraw-Hill Companies Dermis Epidermis Dermal side of the Epidermal dermal interface Slide 29: Slide 29: Thick Skin (ventral surface of finger) Dermal papillae Meissners corpuscles in dermal papillae Epidermal peg Dermis Epidermis Meissners corpuscle is a mechanoreceptor nerve ending for sensitivity to light touch; you would find more on your fingers because they are more sensitive to touch than your elbow. Epidermis Skin hand monkey 109 Hypodermis Papillary layer Epidermal peg Dermal papillae Skin hand monkey 109 Hypodermis Papillary layer Epidermal peg Dermal papillae Adipocytes Eccrine sweat glands Pacinian corpuscles Obesity is characteristic of having a thickened subcutaneous layer LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS STRATUM GRANULOSUM KERATOHYALIN GRANULES LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS STRATUM GRANULOSUM KERATOHYALIN GRANULES STRATUM SPINOSUM TONOFIBRILS - DESMOSOMES LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS STRATUM GRANULOSUM KERATOHYALIN GRANULES STRATUM SPINOSUM TONOFIBRILS - DESMOSOMES STRATUM BASALE CONTINUAL RENEWAL OF EPIDERMIS Slide 29: Slide 29: Thick Skin (ventral surface of finger) cont. 5. Stratum basale Hemidesmosomes 4. Stratum spinosum 3. Stratum granulosum 2. Stratum lucidum 1. Stratum corneum Desmosomes Keratohyalin granules Slide 29: Slide 29: Thick Skin on finger cont. Stratum basale Hemidesmosomes Stratum spinosum Stratum granulosum Stratum lucidum Desmosomes Keratohyalin granules 1 S. granulosum: flattened cells undergoing the terminal differentiation process of keratinization forming the skins barrier against water loss when sealed with contents of membrane coating granules.. Slide 29: Slide 29: Thick Skin on finger cont. Stratum basale Hemidesmosomes Keratohyalin granules 1 The epidermis of thick skin is subject to continuous friction and pressure so the abundant desmosomes (and tonofibrils) withstand this and hold the cell layers together. Stratum spinosum Dermis Epidermis Desmosomes STRATUM CORNEUM STRATUM GRANULOSUM STRATUM SPINOSUM STRATUM BASALE STRATUM SPINOSUM EM 8g of skin: Note the different layers and the cellular contents of each 1.Stratum corneum 2.Startum granulosum 3.Stratum spinosum STRATUM CORNEUM STRATUM GRANULOSUM STRATUM CORNEUM Cells in EPIDERMIS STRATIFIED SQUAMOUS - CELL TYPES INCLUDE: KERATINOCYTES - MAIN CELL TYPE ECTODERM MELANOCYTES - PIGMENTATION - NEURAL CREST LANGERHANS CELL - IMMUNOLOGIC ROLE MERKEL CELLS - ASSOCIATED WITH NERVE ENDINGS MELANOCYTE PIGMENT SYNTHESIS NEURAL CREST ORIGIN (EYE & CNS) The embryonic origin of melanocytes is the neural crest derivatives that migrate into the embryonic epidermis stratum basale. MELANOCYTE - PIGMENT SYNTHESIS MELANOGENESIS CYTOCRINE SECRETION - PASS MELANIN GRANULES TO KERATINOCYTES CYTOCRINE SECRETION - PASS MELANIN GRANULES FROM MELANOCYTES TO KERATINOCYTES MELANOCYTE - PIGMENT SYNTHESIS LOCATED IN THE STRATUM BASALE CLEAR CELL - NO DESMOSOMAL CONNECTION Slide 31Slide 31: Thin Skin (scalp) Stratum basale Stratum spinosum Stratum granulosum Stratum corneum Slide 31Slide 31: Thin Skin (scalp) Stratum basale Stratum spinosum Stratum granulosum Stratum corneum Melanin capping of nuclei Sun from NASA Slide 31Slide 31: Thin Skin (scalp) 4 Stratum basale Stratum spinosum Stratum granulosum Stratum corneum Melanin capping of nuclei Sun from NASA Melanocytes respond to melanocyte stimulating hormone secreted by the pars intermedia. Melanin granule accumulate over the nuclei of mitotic cells of the stratum basale to protect nuclear DNA from UV damage. 107 MELANOCYTE - PIGMENT SYNTHESIS SUSCEPTIBLE TO HORMONES AND PHYSICAL FACTORS SUN-TANNING SEX DIFFERENCES PREGNANCY MELANOCYTE DENSITY - SIMILAR IN ALL HUMANS MELANOCYTE - PIGMENT SYNTHESIS FRECKLES - MELANIN DISTRIBUTED IN PATCHES MELANOCYTE disease states ALBINISM - FAILURE TO PRODUCE MELANIN MALIGNANT MELANOMAS - CANCER ADDISONS DISEASE - PIGMENT DEPOSITION IN SKIN DUE TO ADRENOCORTICAL INSUFFICIENCY LANGERHANS CELLS BONE MARROW ORIGIN LOCATED IN STRATUM SPINOSUM - GOLD CHLORIDE STAIN CLEAR CELL - NO DESMOSOMES DENDRITIC CELL LANGERHANS CELLS DENDRITIC CELL ROD OR RACKET SHAPED GRANULES FUNCTION - IMMUNOLOGIC ROLE AS AN ANTIGEN- PRESENTING CELL CONTACT ALLERGIC RESPONSES AND OTHER CELL MEDIATED REACTION OF THE SKIN Epidermal dermal interface MELANIN is produced by MELANOCYTES 107 MELANIN-producing enzymes in MELANOCYTES EPIDERMIS Space of removed dermis 107 face trunk nipple finger Epidermal dermal interface - finger pad Epidermal dermal interface finger pad Skin, foot 408 Epidermal dermal interface creates unique finger ridges Slide 30Slide 30: Thick Skin (Pacinian corpuscle and melanin) Pacinian corpuscleMelanin pigment Melanin capping of nuclei Pacinian corpuscles are mechanoreceptors that detect vibration and pressure. 105monkey finger Pacinian corpuscles are mechanoreceptors that detect vibration and pressure monkey finger Pacinian corpuscles Skin, scalp 209 Slide 31Slide 31: Thin Skin (scalp) Hair follicle location Arrector pili muscle Sebaceous glands Copyright McGraw-Hill Companies Skin, scalp 209 Skin, scalp Human Skin, scalp 108 sebaceous glands Skin, scalp Mode of secretion of the sebaceous glands is holocrine where by the sebum is released when cells burst. sebaceous glands Human Skin, scalp 108 Skin, scalp Mode of secretion of the sebaceous glands is holocrine where by the sebum is released when cells burst. sebaceous glands Eccrine sweat glands Human Skin, scalp 108 105 Eccrine sweat glands Slide 66Slide 66: Recto-anal junction Hair follicleEccrine sweat glandsSebaceous gland Simple columnar epithelium of rectum with goblet cells Stratified squamous epithelium of anal wall 66 Slide 66: Slide 66: Recto-anal junction Apocrine sweat gland Sebaceous gland hair MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE APOCRINE SECRETION LOSS OF PART OF APICAL CYTOPLASM AND SOME PLASMA MEMBRANE MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE APOCRINE SECRETION LOSS OF PART OF APICAL CYTOPLASM AND SOME PLASMA MEMBRANE HOLOCRINE SECRETION RELEASE OF WHOLE cell OTHER GLANDS OF EPIDERMAL ORIGIN SWEAT GLANDS ECCRINE - COMMON SWEAT GLAND - LOCAL COOLING APOCRINE AXILLARY REGION - FUNCTION IN ANIMALS SWEAT GLANDS secretions Slide 29: Slide 29: Thick Skin (ventral surface of finger) Eccrine sweat glands Myoepithelial cells Ducts of eccrine sweat glands with stratified cuboidal epithelium Myoepithelial cells are eosinophilic because of the presence of muscle contractile proteins, which contract to expel sweat when needed. SWEAT GLANDS Functional diversity of skin PROTECTS AGAINST INJURY (e.g.,UV light or mechanical stresses) AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES THERMOREGULATION RECEIVES STIMULI FAT METABOLISM THREE TYPES OF GRANULES IN KERATINOCYTES MELANIN SKIN PIGMENT PRODUCED BY MELANOCYTES AND PASSED BY CYTOCRINE SECRETION TO KERATINOCYTES MEMBRANE COATING GRANULES (LAMELLATED GRANULES) WATER PROOFING FUNCTION PRODUCED BY KERATINOCYTES KERATINOHYALIN GRANULES PRODUCED BY KERATINOCYTES THREE TYPES OF GRANULES IN KERATINOCYTES MEMBRANE COATING GRANULES (LAMELLATED GRANULES) Small, ovoid structures from the Golgi containing various lipids and they undergo exocytosis to produce a lipid-rich impermeable layer around the cells of the s. granulosum water proofing. THREE TYPES OF GRANULES IN KERATINOCYTES KERATINOHYALIN GRANULES CHEMICAL NATURE NOT CLEARLY ESTABLISHED RICH IN HISTODINE FORMS MATRIX OF CELLS IN STRATUM CORNEUM, STABILITY DUE TO DISULFIDE BONDS ABSENT IN HAIR AND NAILS Melanocytes in Skin 111 Regeneration of epidermis Clinical Correlation Albinism can be caused by a hereditary defect in tyrosinase activity or the inability of cells to take up tyrosine. Patient with albinism would be more at risk for the development of basal and squamous cell carcinomas as albinism produces skin hypopigmentation so fewer melanin granules to protect nuclear DNA from the ionizing, mutagenic effects of UV radiation. Tyrosine amino acid figure chemistry.about.com. Albino peacock Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY. Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY. William J. Banks, Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA. Hans Elias, et al Histology and Human Microanatomy. John Wiley and Sons, New York, NY. Don W. Fawcett Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA. Don W. Fawcett Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY. Arthur W. Ham and David H. Cormack Histology. J. S. Lippincott Company, Philadelphia, PA. Luis C. Junqueira, et al Basic Histology. Lange Medical Publications, Los Altos, CA. L. Carlos Junqueira, et al Basic Histology. Appleton and Lange, Norwalk, CT. L.L. Langley, et al Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY. W.W. Tuttle and Byron A. Schottelius Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO. Leon Weiss Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY. Leon Weiss and Roy O. Greep Histology. McGraw-Hill Book Company, New York, NY. Nature (http://www.nature.com), Vol. 414:88,2001. A.L. Mescher 2013 Junqueiras Basis Histology text and atlas, 13 th ed. McGraw Many illustrations in these VIBS Histology YouTube videos were modified from the following books and sources: Many thanks to original sources! The End!