Epithelial tissue Dept. Histology and Embryology, Faculty of Medicine MU pvanhara@med.muni.cz Petr Vaňhara, PhD § Typical morphology and cell connections General characteristics of epithelium § Avascular (without blood supply) – nutrition by diffusion from a highly vascular and innervated area of loose connective tissue (lamina propria) just below the basement membrane § Highly cellular – cohesive sheet or groups of cells with no or little extracellular matrix § Cell surface specialized for absorption, secretion or barrier Basement membrane •Attachment of epithelium to underlying tissues •Selective filter barrier between epithelial and connective tissue •Communication, differentiation, tissue integrity PAS HE http://stevegallik.org/sites/histologyolm.stevegallik.org/images/SiCuEpi2.gif Basement membrane Two basic layers –lamina basalis •lamina densa, •lamina rara ext. et int. –lamina fibroreticularis Basement membrane •Glycosaminoglycans – heparansulphate •Laminin, collagen III, IV, VI Basement membrane Tissue specific distribution -Descemet’s membrane (BM under endothelial layer of cornea) -Glomerular basement membrane (Bowman capsule) -part of Bruch’s membrane in retina -Many others Clinical correlations - Membranous glomerulonephritis - circulating antibodies bind to glomerular basement membrane - complement (C5b-C9) complex forms and attacks glomerular epithelial cells - filtration barrier is compromised - proteinuria, edema, hematouria, renal failure http://www.ndt-educational.org/images/p2_2.jpg ferrariomg MC900405926[1] Epithelial cell www.webanatomy.net Modifications of cell membrane – cell junctions Zonula occludens – a tight junction Cellular tight junction en.svg File:Tight junction blowup.jpg http://www.cytochemistry.net/cell-biology/membr18.jpg Modifications of cell membrane – cell junctions Zonula occludens – a tight junction Modifications of cell membrane – cell junctions Zonula adherens File:Adherens Junctions structural proteins.svg Cover image expansion (Farquhar, M.G., and Palade, G.E. Junctional Complexes in Various Epithelia, J. Cell Biol.17, 375-412, 1963) http://www.hubrecht.eu/research/derooij/images/RegulationofVE-cadherinduringangiogenesis002_000.jpg Cell adhesion is a regulated event http://www.hubrecht.eu/research/derooij/research.html File:Desmosome cell junction en.svg Modifications of cell membrane – cell junctions Desmosome - a spot junction Cover image expansion (Farquhar, M.G., and Palade, G.E. Junctional Complexes in Various Epithelia, J. Cell Biol.17, 375-412, 1963) http://drugster.info/img/term/hemidesmosome-6933_0.jpg Modifications of cell membrane – anchoring junctions Hemi-desmosome - a spot junction http://wiki-images.enotes.com/thumb/4/46/Ultrastructure_of_tracheal_hemidesmosomes_in_mice.JPEG/300 px-Ultrastructure_of_tracheal_hemidesmosomes_in_mice.JPEG doi:10.1186/1465-9921-7-28. -Stable, resistant structures -Protection against shear or mechanical damage -Cornea, skin, oral cavity and esophagus -Anchoring structure for intermediate filaments (cytokeratins) Modifications of cell membrane – anchoring junctions Focal adhesions -FA connect actin filaments and basal membrane -Dynamic structures, capable of intracellular signaling -Molecular basis for cell migration Modifications of cell membrane – cell junctions Nexus – gap junctions File:Gap cell junction en.svg http://www.cytochemistry.net/cell-biology/membr20.jpg Modifications of cell membrane – cell junctions Nexus – gap junctions http://2.bp.blogspot.com/-NmnB6BO-sR8/TaWnopxLVKI/AAAAAAAAABE/aV9rNgNqelY/s1600/cell_junctions.jpg Modifications of cell membrane – cell junctions Summary Soubor:Ultrastructure of choroid epithelium.jpg Modifications of cell membrane – basal cell surface Basal labyrinth Modifications of cell membrane – apical cell surface Microvilli http://www.cytochemistry.net/cell-biology/membr23.jpg http://www.mc.vanderbilt.edu/histology/word/2004/Cell%20Junctions%2004_files/image002.jpg http://www.anatomybox.com/wp-content/uploads/2012/02/600brush-border.jpg Modifications of cell membrane – apical cell surface Brush border http://cms-histologyproject1-group13.wikispaces.com/file/view/EM---Brush-Border.gif/50343623/EM---B rush-Border.gif Modifications of cell membrane – apical cell surface Stereocilia http://www.cmb.northwestern.edu/faculty/james_r_bartles_files/bartles/stereocilia1.jpg http://www.d.umn.edu/~jfitzake/Lectures/DMED/InnerEar/IEPathology/Figures/NormalHC.jpg - e.g. inner ear - not actively moving - like microvilli, with parallel microfilaments - sensory apparatus Modifications of cell membrane – apical cell surface Kinocilia http://www.visualphotos.com/photo/1x8466962/mammalian_sperm_tail_9l8648.jpg Modifications of cell membrane – apical cell surface Kinocilia http://img.tfd.com/dorland/spermatozoon.jpg Modifications of cell membrane – apical cell surface Summary Microvilli Brush border Stereocilia Kinocilia Break MC900293200[1] Trávící systém III - 1 Játra - schéma Trabecular epithelium (Liver) Classification of epithelial tissues Reticular epithelium (Thymus) Classification of epithelial tissues Surface epithelium Classification of epithelial tissues Classification of epithelial tissues Epithelium may posses a function Glandular epithelium •Secret ↔ excret •Process of secretion: Glandular epithelium •Single cell –Goblet –Enteroendocrine Epitelová tkáň - 20 Pohárkové buňky - schéma Epitelová tkáň - 22 Poh Goblet cells -Mainly respiratory and intestinal tract -Produce mucus = viscous fluid composed of electrolytes and highly glycosylated glycoproteins (mucins) -Protection agains mechanic shear or chemical damage -Trapping and elimination of particular matter -Secretion by secretory granules constitutive or stimulated -After secretion mucus expands extremely – more than 500-fold in 20ms -Dramatic changes in hydration and ionic charge -Chronic bronchitis or cystic fibrosis – hyperplasia or metaplasia of goblet cells - - http://www.vivo.colostate.edu/hbooks/pathphys/misc_topics/goblet_he.jpg •Multicellular –Endoepithelial – –Exoepithelial •Shape of secretion part –Alveolar –Tubulous –Tuboalveolar •Branching –Simple –Branched –Compound •Secretion –Mucous –Serous –Compound http://www.mc.vanderbilt.edu/histology/labmanual2002/labsection1/GlandularEpithelium03_files/image0 06.jpg Development of glands Mucous glands Mucous glands Serous glands Epitelová tkáň - 31 Smíšená žláza Compound glands - both serous and mucous Cells secreting proteins - large, light nucleus with dominant euchromatin - developed GER - GA/secretory vesicles depend on fate of proteins - secret of low viscosity – serous secretion http://cytochemistry.net/cell-biology/medical/06_016.jpg http://www.visualhistology.com/products/atlas/VisualHistology_Atlas_2-0-19_1.jpg Cells secreting polypeptides/biogenic amines - Specific secretory vesicles, 100-400 nm - Content of vesicles differs in different cell types – argentaphilic, argyrophylic, chromatophilic - e.g. APUD cells with hormone or parakrine signaling capability http://class.kmu.edu.tw/~wags/Biology/Wags/histopage/empage/ei/ei1.gif http://www.mc.vanderbilt.edu/histology/images/histology/gi/display/gi-0029.jpg Cells secreting mucus - Specific secretory vesicles - Secretion of high viscozity – mucous secretion - Rich in glycoproteins - RER, GA - granules of fibrogranular appearance - e.g. goblet or foveolar cells http://www.sciencephoto.com/image/309992/large/P5200106-TEM_of_goblet_and_secretory_cells_in_duoden um-SPL.jpg Paneth Cell Cells secreting steroids - SER well developed - Mitochondria with tubules - Lipid droplets http://www.pathologyimagesinc.com/emhandbook/tumor-recogn-section/images/4-4a-adreno.jpg http://www.pathologyimagesinc.com/emhandbook/tumor-recogn-section/tumor-pages/adrenocortical.html Cells transporting ions - Membrane invaginations – basal labyrinth - Acidophilic cytoplasm - e.g. proximal tubules of kidneys, striated duct in salivary glands Figure 8 http://neuromedia.neurobio.ucla.edu/campbell/glands/wp_images/128%20striated%20duct.jpg Epithelium may posses a function Sensory epithelium – olfactory epithelium http://media-3.web.britannica.com/eb-media/59/55759-004-CB892C59.jpg http://www.anatomyatlases.org/MicroscopicAnatomy/Images/Plate297.jpg Figure 22-11. Auditory hair cells. Figure 22-13. How a sensory hair cell works. Epithelium may posses a function Sensory epithelium – inner ear Epithelium may posses a function Sensory epithelium - retina Figure 22-14. The structure of the retina. http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2010/2010%20Exam%20Reviews/Exam%204%20R eview/retina_layers.jpg Clinical correlations - Metaplasia Squamous metaplasia of the uterine cervix Simple columnar Simple columnar Stratified squamous MC900405926[1] http://static.jci.org/content_assets/manuscripts/38000/38019/large/JCI38019.f1.jpg http://static.jci.org/content_assets/manuscripts/38000/38019/large/JCI38019.f1.jpg Clinical correlations – EMT in development and disease MC900405926[1] Clinical correlations – EMT in development and disease http://static.jci.org/content_assets/manuscripts/38000/38019/large/JCI38019.f5.jpg J Clin Invest. 2009;119(6):1438–1449. doi:10.1172/JCI38019. MC900405926[1] Thank you for attention pvanhara@med.muni.cz mu http://www.med.muni.cz/histol/histolc.html