Epithelium and glands
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Transcript of Epithelium and glands
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EPITHELIUM AND GLANDSDr. Larry Johnson
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Objectives• Identify every epithelium present in any tissue section. • Differentiate between mucus and serous secreting
epithelia. • Identify single-celled glands, endocrine glands and the
various types of exocrine glands. • Detail the structure of the sebaceous gland. • Identify the different types of sweat glands and distinguish
the duct from the secretory region. • Identify myoepithelial cells and know their function.
From: Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory Manual
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ORIGIN AND DISTRIBUTION OF EPITHELIUM
ECTODERM - EPIDERMIS OF SKIN AND EPITHELIUM OF CORNEA TOGETHER COVERS THE ENTIRE SURFACE OF THE BODY; SEBACEOUS AND MAMMARY GLANDS
ENDODERM - ALIMENTARY TRACT, LIVER, PANCREAS, GASTRIC
GLANDS, INTESTINAL GLANDS• ENDOCRINE GLANDS - LOSE
CONNECTION WITH SURFACE
MESODERM• ENDOTHELIUM - LINING OF BLOOD VESSELS• MESOTHELIUM - LINING SEROUS CAVITIES
ECTODERM
ENDODERM
MESODERM
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Characteristics of epithelium• Classification by # of layers
• Simple = single layer• Stratified = multiple, stacked
layers• Pseudostratified = appears to be
multiple layers, but all cells touch basement membrane (all cells do not necessarily reach lumen)
• Classification by shape• Squamous = flat• Cuboidal = square• Columnar = column
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Laboratory Experience• Identify and characterize various types of epithelia
• Recognize various glands and modes of secretion
• Recognize gland associated structures/cells and differentiate glands from their ducts
• Understand significance of cytological expression of epithelial cells with regard to function
053 Slide 93Slide 35Slide 53
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Slide 33: Kidney (PAS/hematoxylin)
Basement membrane
Brush border
Periodic acid – Schiff • Used to visualize: glycogen, glycoproteins, and glycosaminoglycans• Steps in PAS staining
1. Periodic acid oxidizes 1,2-glycols to aldehydes2. Schiff’s reagent colors the aldehyde groups (pink to magenta)
The brush border is composed of numerous microvilli which function to increase surface area for absorption of nutrient material and fluid.
The structure on the brush border that stains with periodic-acid Schiff (PAS) stain is the glycocalyx.
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EM 1 & 7
Observe various brush border - microvilliThe brush border is composed of numerous microvilli of a uniform size projecting into a lumen. Each microvillus is composed of microfilaments (actin) surrounded by the cell membrane.
glycocalyx
PASstaining
Slide 33
Lipid in SER
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EM 2
Stereocilia of the epididymis - long thin microvilli
Stereocilia are very long, branched, non-motile microvilli of differing lengths that function in absorption from the lumen.
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EM 5 & 6
Observe cell junctions characteristic of epithelium
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SPECIALIZATION OF EPITHELIAMAINTAIN EXTENSIVE
CONTACTS AMONG CELLSSTRUCTURALLY AND FUNCTIONALLY POLARIZED
JUNCTIONSZONULA OCCLUDENS - TIGHT JUNCTION (BELT)ZONULA ADHERENS –
ADHERING BELTDESMOSOME (MACULA
ADHERENS) - SPOT ATTACHMENTGAP JUNCTIONS - COMMUNICATION
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Terminal bars
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Slide 32: Kidney (H&E)
Simple squamous Simple squamous
Simple cuboidal Simple cuboidal
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Slide 75: Thyroid gland (endocrine)
Simple cuboidal epithelium Basement membrane
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SUMMARY OF TISSUE FEATURES OF EPITHELIUM
• AVASCULAR• EXTRANEOUS CELLS
• REGENERATION• MIGRATION
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SUMMARY OF TISSUE FEATURES OF EPITHELIUM
• AVASCULAR• EXTRANEOUS CELLS
• REGENERATION• MIGRATION
• METAPLASIA• BASEMENT MEMBRANE
Slide 258
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SECRETION – ACTIVE PROCESS CONSUMING ENERGY
EXOCRINE GLANDS - DELIVER THEIR SECRETION INTO DUCTS OPENING INTO EXTERNAL OR INTERNAL SURFACE
ENDOCRINE GLANDS - DUCTLESS, DELIVER THEIR SECRETIONS INTO THE LYMPH OR BLOOD STREAM
PANCREAS has endocrine
PANCREAS has exocrine
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EXOCRINE GLANDSDUCT
• SIMPLE - UNBRANCHED DUCT• COMPOUND - BRANCHED DUCT
SECRETORY PORTION• TUBULAR• COILED TUBULAR• BRANCHED TUBULAR• ALVEOLAR• BRANCHED ACINAR• TUBULOACINAR• TUBULOALVEOLAR
MUCUS VS SEROUS
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TUBULARCOILED TUBULARBRANCHED TUBULARALVEOLAR
BRANCHED ACINARTUBULOACINARTUBULOALVEOLAR
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ACINUS = FUNCTIONAL UNIT
SEROUS MUCOUS
Mucous - Light staining Cytoplasm and dark, flattened nucleus at base of cell
Serous – dark red staining cytoplasm and lighter, spherical nucleus
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Slide 072: Submandibular gland
Simple columnar epithelia Stratified columnar epithelia
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Slide 072: Submandibular gland
Serous cells Mucous cells Serous demilune
The submandibular gland is a mixed (seromucous) gland whose mode of secretion is merocrine secretion = exocytosis without loss of cellular components
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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 CYTOCRINE SECRETION – MELANIN GRANULES TRANSFERRED FROM MELANOCYTE TO KERATINOCYTES
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MEROCRINE APOCRINE
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CYTOCRINE SECRETION - PASS MELANIN GRANULES FROM MELANOCYTES TO KERATINOCYTES
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Slide 61: Terminal Ileum
Goblet cell releasing contents
Simple columnar epithelium
Brush border composed of microvilli
Microvilli are fingerlike projections that greatly increase the surface area of certain cells to help increase absorption. Microvilli are non-motile and are composed of a core of thin microfilaments called actin.
Alternative slide 250
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Slide 40: Trachea
Ciliated pseudostratified columnar epithelium with
goblet cells
Goblet cell releasing contents
The main function of cilia is to sweep or move fluids, cells, or particulate matter across cell surface in the lumen as to remove dust in the lungs. Microtubules of the axoneme are at the core of cilia and make them motile..
Note the thick basement membrane of the respiratorypseudostratified columnar epithelium.
Alterative slide 242
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Slide 93: Epididymis
Pseudostratified columnar epithelium with stereociliaMicrovilli: small, non-motile projections composed of thin microfilamentsStereocilia: long, non-motile projections (branched microvilli) composed of thin microfilamentsCilia: larger, long, motile projections composed of thick microtubules
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Slide 35: Urinary bladder
Specialized “dome-shaped” cells
Basal cells
Transitional epithelium
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Slide 34: Ureter
Transitional epithelium
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Stratified squamous epithelium: the protection epithelium
• Keratinized stratified squamous (thick or thin)• Prevent dessication• Protect against abrasion• Prevent foreign invasion• Ex. Slide 29: Thick skin (ventral
surface of finger)
• Non-keratinized stratified squamous• Moist lubricated surface• Ex. Slide 52: Tongue
Slide 029
Slide 52
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Slide 52 : Tongue
Non-keratinized stratified squamous epithelium
Mucous acini Serous acini
Mucous cells stain light and serous cells stain dark.
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Slide 53: Esophagus
Non-keratinized stratified squamous epithelium
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Slide 29: Thick skin (ventral surface of finger)
Epidermis withkeratinized stratifiedsquamous epithelium
Dermis
Hypodermis
The major function of this type of epithelium (thick skin) is for protection from mechanical stress, but it also prevents dehydration.
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Slide 29 : Thick skin (ventral surface of finger)
Keratinized stratified squamous epithelium
Polyhedral cells
Cuboidal cells of the stratum basale
The cells in the stratum basale serve as stem cells for the epidermis, and their progeny differentiate as they move away from the base.
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Slide 29 : Thick skin (ventral surface of finger)
Duct of eccrine sweatgland with stratifiedcuboidal epithelium
Eccrine sweat gland
Myoepithelial cells
Myoepithelial cells are eosinophilic because of the presence of a high density of contractile protein. These cells surround the gland like a net and expel glandular secretions upon contraction.
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Slide 31: Thin skin (scalp)
Keratinized, stratifiedsquamous epithelium
Sebaceous glands
The mode of secretion used by sebaceous glands is holocrine secretion
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Slide 66: Recto-anal junction
Rectum - simple columnar epitheliumAnus – stratified squamous
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Slide 66 : Recto-anal junction
Eccrine sweat glandSebaceous glands Apocrine sweat gland
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GLANDS OF EPIDERMAL ORIGIN
SWEAT GLANDS• ECCRINE - COMMON
SWEAT GLAND - LOCAL COOLING
• APOCRINE AXILLARY REGION - FUNCTION IN ANIMALS,
discharge in hair follicle
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Epithelial tissues of the body
• Use table as guide
• Generalizations• Entire GI system from
gastro-esophageal junction to recto-anal junction is lined by simple columnar epithelium
• Cilia is present in most respiratory passages
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EPITHELIA ARE SPECIALIZED FOR FUNCTIONS
ABSORPTION - INTESTINESECRETION - PANCREASTRANSPORT - EYE, ENDOTHELIUM IN VESSELSEXCRETION - KIDNEYPROTECTION – AGAINST
MECHANICAL DAMAGE AND DEHYDRATION
SENSORY RECEPTION – PAIN TO AVOID
INJURY, TASTE BUDS, OLFACTORY, ETC.
CONTRACTION – MYOEPITHELIUM
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SURFACE SPECIALIZATIONS OF EPITHELIA
MICROVILLI - INTESTINE ABSORPTIVE CELLCILIA - RESPIRATORY EPITHELIUM
BASAL LAMINA – ALL EPITHELIUM
INTERCELLULAR CANALICULUS – HEPATOCYTE
SECRETORY CANALICULUS – GASTRIC PARIETAL CELL
FLAGELLA
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SURFACE SPECIALIZATIONS OF EPITHELIA
INTERCELLULAR CANALICULUS – HEPATOCYTE
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SURFACE SPECIALIZATIONS OF EPITHELIA
SECRETORY CANALICULUS – GASTRIC PARIETAL CELL
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Clinical Correlation
Normal larynx with ciliated pseudostratified columnar epithelium
Abnormal larynx with stratified squamous epithelium
Edward C. Klatt, M.D.Mercer University School of Medicine
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• Bruce Alberts, et al. 1983. Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.• Bruce Alberts, et al. 1994. Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
• William J. Banks, 1981. Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA.
• Hans Elias, et al. 1978. Histology and Human Microanatomy. John Wiley and Sons, New York, NY.
• Don W. Fawcett. 1986. Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA.
• Don W. Fawcett. 1994. Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY.
• Arthur W. Ham and David H. Cormack. 1979. Histology. J. S. Lippincott Company, Philadelphia, PA.
• Luis C. Junqueira, et al. 1983. Basic Histology. Lange Medical Publications, Los Altos, CA.
• L. Carlos Junqueira, et al. 1995. Basic Histology. Appleton and Lange, Norwalk, CT.
• L.L. Langley, et al. 1974. Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY.
• W.W. Tuttle and Byron A. Schottelius. 1969. Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO.
• Leon Weiss. 1977. Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY.• Leon Weiss and Roy O. Greep. 1977. Histology. McGraw-Hill Book Company, New York, NY.
• Nature (http://www.nature.com), Vol. 414:88,2001.
• A.L. Mescher 2013 Junqueira’s Basis Histology text and atlas, 13th ed. McGraw
• Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory Manual - Slide selections were largely based on this manual for first year medical students at TAMHSC
Many illustrations in these VIBS Histology YouTube videos were modified from the following books and sources: Many thanks to original sources!
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The End!