EPITHELIUM

					EPITHELIUM
   - protection, absorption, secretion, transport, sensory reception, etc

                            Appearance                     Location/Example              Function            Image
Simple                                                 - Bowman’s capsule
Squamous                                               - cornea
                                                       - mesothelium
                                                       - endothelium



Simple        width ~ height                           - kidney collecting        - lines ducts or tubules
Cuboidal                                               duct/tubule
                                                       - distribution variable,
                                                       depends on species



Simple        - surface mods (microvilli,              - stomach                  - absorptive
Columnar      glycocalyx)                              - intestine                - secretory
              - junctional complexes (tight junction   - gall bladder
              (occludens), desmosome (adherens),
              gap junction) at lateral borders

Pseudostrat   - irregular shape and thickness          - respiratory tract        - movement of fluid,
Columnar      - nuclei at different levels             - reproductive tract       mucociliary clearance
              - all cells reach basement membrane                                 - secretory –
              - basal cells = stem cells                                          endo/exocrine
              - secretory cells = glandular epithel,                              - sensory (neuroepithel)
              unicellular (serous or mucous)                                      - brush cells =
                                                                                  chemoreceptors
                             Appearance                   Location/Example               Function          Image
Stratified    Keratinized: 5 strata:                  - skin                     - protection (skin)
Squamous      1. basale (germinativum) – stem cells   - ruminant forestomach     - absorption (stomach)
              2. spinosum – prickly cells
              3. granulosum – keratohyalin granules
              (4. lucidum – only in thick)
              5. corneum – no nuclei, keratin,
              intercellular lamellar bodies  water
              impermeable and protective

              Non-Keratinized:                        - esophagus of carnivore
              similar to keratinized but no
              keratinized layer
              - top layer = Str. superficiale – has
              nuclei but they are pyknotic


Stratified                                            - mammary glands           - lines large ducts
Cuboidal                                              - sweat glands             (lobar or excretory
                                                      - salivary glands          ducts) of glands


Transitional - stratified polyonal                    - urinary system (bladder, - allow distention
                                                      ureter, renal pelvis)      - protect v osmostic
                                                      - palpebral conjunctiva    pressure, chem. insults
                                                      - naso-pharynx

				
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posted:8/20/2011
language:English
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