•Epithelial tissue •Dept. Histology and Embryology •Faculty of Medicine MU • •pvanhara@med.muni.cz •Petr Vaňhara, PhD •General characteristics of epithelium § Lining of cavities or interfaces of open space § Inner linings of vessels – endothelia § Visceral and parietal mesothelium – lining of pleura, peritoneum, pericardium § Clusters or cords of cells with secreting function § Resorptive, sensory or simply protective functions • § § § gal753_t43 § 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 •General characteristics of epithelium •Basement membrane •Attachment of epithelium to underlying tissues •Selective filter barrier between epithelial and connective tissue •Communication, differentiation •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 (under endothelial layer of cornea) -Glomerular basement membrane (Bowman capsule) -part of Bruch’s membrane in retina -…. Pathology example- 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 •Classification of epithelial tissues •Vessels •Kidney •Intestine •Respiratory passages •Skin •Oesophagus •Ducts •Urinary tract •Covering epithelium Trávící systém III - 1 Játra - schéma •Trabecular epithelium •(Liver) •Classification of epithelial tissues Langerhans islets http://upload.wikimedia.org/wikipedia/commons/e/e1/Mouse_islet_LM_SolimenaLab.jpg File:Langerhanssche Insel.jpg 14192066-drawing-of-a-pancreatic-islet-of-langerhans-showing-the-alpha-beta-and-delta-hormone-produ cing-cells File:Adrenal gland (cortex).JPG File:Gray1185.png Adrenal cortex Adenohypophysis – anterior pituitary ENDO093 Anterior Pituitary 100X magnification rathke •Reticular epithelium •(Thymus) •Classification of epithelial tissues Epithelium may posses a function •Process of secretion: §Glandular epithelium 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 glands –Endoepithelial – –Exoepithelial •Shape of secretion part –Alveolar –Tubulous –Tuboalveolar •Branching –Simple –Branched –Compound •Secretion –Mucous –Serous –Compound •Multicellular glands –Endoepithelial • –Exoepithelial •Shape of secretion part –Alveolar –Tubulous –Tuboalveolar •Branching –Simple –Branched –Compound •Secretion –Mucous –Serous –Compound Mucous glands •Mucous glands Serous glands Epitelová tkáň - 31 Smíšená žláza Compound glands - both serous and mucous component §Respiratory epithelium •Respiratory passages –Moisten, protect against injury and pathogen –Remove particles by „mucociliary escalator“ –Pseudostratified columanr epithelim with cilia –Basal cells- epithelium renewal slide5 •Alveolar epitheithelium –Gas exchange –Respiratory bronchiols, alveolar passages and alveoli –Type I and II pneumocytes alveoliHe §Sensory epithelium –Supportive and sensory cells •Primary sensory cells – directly convert stimulus to membrane potential •Receptory region, body, axonal process •Nasal epithelium (regio olfactoria nasi), rods and cones • •Secondary sensory cells •Receptory region and body •Signal is trasnimtted by adjacent neurons ending on secondary sensory cell •Taste buds, vestibulocochlear appartus image004 TasteBud §Myoepithelium –Star-like or spindle cells –Connected by nexus and desmosomes –Actin microfilaments, myosin and tropomysoin –Contraction –Sweat and salivary glands – enhance secretion F1 File:Testicle-histology-boar.jpg •Clinical correlations - Metaplasia •Squamous metaplasia of the uterine cervix •Simple columnar •Stratified squamous •Clinical correlations – Epithelial to mesenchymal transition emt nrc1549-f1 Oral_cancer_%281%29_squamous_cell_carcinoma_histopathology Cancer •Thank you for attention •pvanhara@med.muni.cz mu •http://www.med.muni.cz/histology