Glandular Epithelium

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Glandular Epithelium
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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)

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Gland Categories

• Presence or absence of ducts
• Exocrine ducted
• Endocrine - ductless
• Uni- or multicellular
• Mode of secretion
• D) Secretion products

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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

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Cellular Composition

• 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).

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Mucous Secretory Gland Esophagus
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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.

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Apocrine Secretion Mammary Gland
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Epithelial Polarity
Absorption Secretion
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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.

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Serous (pancreatic acinar) cell
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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.

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Myoepithelial Cell In Salivary Gland
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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

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DNES Cell With Secretory Granules
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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.