Types of Epithelial Tissue PDF

TYPES OF TISSUE EPITHELIAL TISSUE Ass.dr.Ema Bexheti What is epithelial tissue? Epithelial are diverse group of tissues that include both surface epithelia and solid organs. They are avascular do not contain blood vessels nor lymph nodes. Cells are in close contac...

TYPES OF TISSUE EPITHELIAL TISSUE Ass.dr.Ema Bexheti What is epithelial tissue? Epithelial are diverse group of tissues that include both surface epithelia and solid organs. They are avascular do not contain blood vessels nor lymph nodes. Cells are in close contact wit only minimal amount of intracellular substance. Epithelialtissue covers the surface of the body, forms the lining of hollow organs (digestive tract airways, and lungs, urinary and genital tracts and forms parenchyma of the glands and the lining of their ducts. Characteristics of epithelial 1 They are in close contact 2 They sit on basal lamina 3 They exhibit functional and morphological polarity. 3.1 apical pole 3.2 basal pole 3.3 lateral domain 4 High regeneration ability 5 Cytoskeleton contains cytokeratin intermediate filaments How are epithelial classified? Arrangement of the cells ( surface, trabecular reticular) The number of layers ( simple, pseudostratified, stratified) The shape of the cells ( cuboidal, columnar or squamos) Dominant functions ( Sensory, transport, respiratory, secretory…. Ectera..) Simple squamous epithelia Passive transfer of substances (osmosis and diffusion) In higher epithelia the transfer of substances is often facilitated by specialized transporters embedded in their cell membrane. Active transport- dependent on energy source. 1.Simple squamous epithelia 1.1Simple cuboidal epithelium 1.2Simple columnar epithelium 1.2.1Simple columnar ciliated epithelium 1.3 Pseudostratified columnar ciliated epithelium Stratified surface epithelia Multiple layers of cells meaning lower permeability Provide covering and protection Stratified squamos epithelium –most resistant epithelium Keratinized ( with a nuclei) ,and Non-keratinized ( without a nuclei) *Keratinized skin, terminal section of male urethra, anal canal (weakly keratinized) Non-keratinized  oral cavity, esophagus, pharynx, nasal vestibule and vocal chords in larynx, vagina and vaginal vestibule. Stratified surface epithelia Transitional epithelium Consists of three layers or rows 1 basal row-multi wall basal cells 2 middle row-pear shaped cells 3 surface row – umbrella cells some which gradually loose contact with basement membrane ( it becomes separate layer. Transitional epithelium Transitional epithelium location Minor renal calyces and renal calyces Renal pelvis Ureters Urinary bladder Urethra Types of epithelia Trabecular Trabecular epithelium of an epithelium endocrine gland-adrenal cortex (zona fasciculata) Follicular endocrine glandular epithelium-thyroid gland Reticulare epithelium of developing tooth Stratified squamous non-keratinized epithelium in the oral cavity. Stratified squamous non- keratinized epithelium in the oral antrum Pseudostratified ciliated columnar epithelium on the epiglottis Surface epithelium and secondary sensory epithelium of the mucous membrane of a vallate lingual papilla Epithelia and glands