; Glandular Epithelium
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Glandular Epithelium

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									Glandular Epithelium
      Glandular Epithelium
• Glandular Epithelium: epithelium of cells
  specialized to produce secretion. All
  glands are of composed of epithelium.
• Secretion – Exocytotic release of products,
  not metabolic wastes
• Molecules to be secreted may be stored in
  membrane bound secretory granules
  (vesicles)
          Gland Categories
A) Presence or absence of ducts
  •   Exocrine – ducted
  •   Endocrine - ductless
B) Uni- or multicellular
C) Mode of secretion
D) Secretion products
          Gland Categories

1) Exocrine - glands that exude secretions
  into a ductule system. Have two parts,
  acinous = secretory bulb and ductule.
2) Endocrine - glands exuding secretions
  directly into body fluids, ultimately blood.
3) Mixed - glands combining both the above
  characteristics (e.g. liver) in the same cell
4) Paracrine - tissue secretions affecting
  own cells
         Cellular Composition
1) Unicellular - single cell gland, Goblet cell;
      mucous secreting. GI tract, respiratory ducts.
      Secretion process alters cell and nucleus shape.
2) Multicellular -
   a) intra epithelial gland -
      gland is entirely within a layer of epithelium.
      Common in pseudostratified columnar epith.
   b) extra epithelial gland - in CT below epithelium; may
      have different shapes; tubular and saccular (acinar).
Mucous Secretory Gland
     Esophagus
        Modes of Secretion
     (how products leave the cell)

1) merocrine - secretion does not affect the
     well-being of the cell = sweat glands.
2) apocrine - small part of the cell cytoplasm is
     lost with the secretion; the cell is damaged
     but not killed = mammary glands.
3) holocrine - great deal of cytoplasm is lost with
     the secretion; the cell dies. Sebaceous
     glands.
Apocrine Secretion
 Mammary Gland
      Epithelial Polarity




Absorption           Secretion
         Secretion Products
1) serous - thin, watery fluid, product of serous
     cells, small pink staining cuboidal cells with
     spherical to elliptical nuclei; salivary glands,
     sweat glands, pancreatic acinar.
2) mucous - thicker, viscous secretion, product of
     mucous cells, large blue staining cuboidal
     cells with flat, elongate nuclei; GI tract, oral
     cavity.
3) mixed serous-mucous - oral cavity, salivary.
4) sebaceous - thick, lipid rich secretions of
     cuboidal cells in certain skin regions - face,
     nose, axillary and pubic regions.
Serous (pancreatic acinar) cell
            Myoepithelium
• Myoepithelium - specialized squamous
  epithelial cells with powers of contraction;
• Surround glandular acini and ducts of
  many glands,
• Contain actin, myosin, cytotokeratin =
  definitely epithelial in origin, not muscle.
Myoepithelial Cell
In Salivary Gland
  Diffuse Neuroendocrine System
             (DNES)
• Paracrine secretion of norepinephrine or
  serotonin in non-endocrine tissue
• Derived from Neural Crest Cells
• About 35 types of cells in a variety of
  tissues such as respiratory, urinary,
  gastrointestinal, pituitary, thyroid
• System formerly known as APUD cells
  – Amine Precursor Uptake Decarboxylation
      DNES Cell
With Secretory Granules
       Secretory Membranes
• Similar names of secretion products;
      names based upon type of secretions; form
      organs (peritonea, gut tube lining, etc.)

  1) Serous Membrane - thin, flat layer of squamous
      epithelial cells which is moistened by exudates from
      underlying blood vessels.

  2) Mucous Membrane - moist epithelial surface,
      usually columnar, but may be cuboidal or squamous,
      that is moistened by secretions produced by glands
      formed by the epithelium itself.

								
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