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DIGESTIVEDIGESTIVEDIGESTIVEDIGESTIVEDIGESTIVEDIGESTIVEDIGESTIVEDIGESTIVE
GLANDSGLANDSGLANDSGLANDSGLANDSGLANDSGLANDSGLANDS
EXTRINSIC/EXTRA-MURAL GLANDS OF DIGESTIVE SYSTEM
���� Salivary Glands ���� Pancreas���� Liver���� Gall Bladder
GENERAL ORGANIZATION AND
COMPONENTS OF DIGESTIVE SYSTEM
Source: Ham. 1957. Histology. 3rd Edition.
EXTRINSIC GLAND/ EXTRA-MURAL GLAND
INTRINSIC GLAND
INTRINSIC GLANDTUBULAR PORTION
TERMS USED TO DESCRIBE THE BRANCHED DUCT SYSTEM
OF LARGE EXOCRINE GLANDS
���� INTERCALATED DUCTS
���� STRIATED DUCTS
���� EXCRETORY DUCTS
���� INTRALOBULAR DUCTS
���� INTERLOBULAR DUCTS
���� INTERLOBAR DUCTS
BASED ON POSITIONIN THE GLAND
BASED ON MORPHOLOGYOF THE EPITHELIUM
Classification of ducts by position in the gland
Blue = CTRed = ducts
Green = gland
tissue
Main Duct(interlobar)
Duct from a lobe(interlobar)
Duct from a
lobule(interlobular)
Duct within alobule
(intralobular)
TERMS USED TO DESCRIBE THE BRANCHED DUCT SYSTEM
OF LARGE EXOCRINE GLANDS
���� INTERCALATED DUCTS
���� STRIATED DUCTS
���� EXCRETORY DUCTS
���� INTRALOBULAR DUCTS
���� INTERLOBULAR DUCTS
���� INTERLOBAR DUCTS
BASED ON POSITIONIN THE GLAND
BASED ON MORPHOLOGYOF THE EPITHELIUM
Morphology of structures associated with
secretory units in digestive glands
From Junqueira et al. 1975
Function of striated ducts
From Junqueira et al. 1975
TERMS USED TO DESCRIBE THE SECRETORY PRODUCTS
OF LARGE EXOCRINE GLANDS
• SEROUS (usually acini)
• MUCOUS (usually tubular, frequently
short)
• MIXED (usually short mucous tubules with
serous cells mixed in near the ends)
SECRETORY EPITHELIAL CELLS of Salivary Gland
As Viewed at TEM Level
Source: Lentz. 1971. Cell Fine Structure.
SecretoryGranules
SecretoryGranules
Forming SecretoryGranules
SEROUS-SECRETING CELL MUCUS-SECRETING CELL
Mucous-secreting cells
Serous-secreting cells
SUBMANDIBULAR SALIVARY GLAND
Mixed secretory unit structure
Oral cavity and pharynx
ORAL CAVITY
PHARYNX
Parotid
Submaxillary or Submandibular
Sublingual
Structures found in major salivary glands
PAROTID SALIVARY GLAND
Serous-secreting Acini
Striated Ducts
Parotid gland
Ross et al. Plate 48
Ross et al. Plate 47
Submandibular(submaxillary)
gland
Mucous-secreting cells
Serous-secreting cells
Submandibular (submaxillary) gland
Sublingual gland
SUBLINGUAL SALIVARY GLAND
Mucous-secreting cells
Serous-secreting cells
Parotid gland Sublingual glandSubmandibular(submaxillary) gland
All serous units (don’t be fooled by adipose) Mostly serous units with areas of mixed units Almost all mixed units
Secretory unit and duct structure in the pancreas
Pancreas
PANCREAS
Islet of Langerhans(endocrine secretion)
Pancreatic acinar cells (exocrine secretion)
Duct
Duct
PancreasParotid gland
COMPARISON OF DIGESTIVE GLANDS
Gland Type of units Striated ducts
Parotid all serous present
Submandibular serous + mixed present
Sublingual all mixed absent or few
Pancreas all serous absent
Liver structure
HEPATOCYTES
Source: Bloom and Fawcett. 1975. A Textbook of Histology. 10th Edition.
As Observed at TEM LevelAs Observed at LM Level
Lobule organization in the liver
HEPATIC LOBULE in pig liver
Bile Duct
HepaticArteriole
Hepatic Portal Venule
PORTAL TRIAD
Source: Bloom and Fawcett. 1975. A Textbook of Histology. 10th Edition.
HEPATIC LOBULE
Hepatic cords/
hepatic plates
STRUCTURE-FUNCTION RELATIONSHIPS WITHIN HEPATIC LOBULE
Source: Ham. 1957. Histology. 3rd Edition.
3-D reconstruction of liver lobule organization
HEPATOCYTES (as seen by LM)
Hepatic cord/hepatic plate
Hepatic sinusoids
Cells associated with liver sinusoids
(phagocytic)
(store vitamin A, produce collagen
in space of Disse)
STRUCTURE-FUNCTION RELATIONSHIPS WITHIN HEPATIC LOBULE
Source: Ham. 1957. Histology. 3rd Edition.
Bile caniculiare formed by
adjacent
hepatocytes
and eventually
empty into the
bile duct branches in
the portal triads
E
Bile caniculiare formed by
adjacent
hepatocytes
and eventually
empty into the
bile duct branches in
the portal triads
Bile Duct
HepaticArteriole
Hepatic Portal Venule
PORTAL TRIAD
Bile duct and gall bladder
Wall structure of the gall bladder
Mucosa
simple columnar
epithelium with
apical microvilli
and lateral
intercellular
spaces
lamina propria of
loose FECT
mucous glands
may be present,
mostly in the neck
region
Muscularis externa
bundled smooth
muscle without
clear layers
Adventitia or serosa
loose FECT +/-
mesothelium
The epithelium of the gall bladder
sometimes extends as a
series of tubular channels or
sinuses into the muscularis. These
channels may become infected.
Gall bladder epithelial
cells extract water from
bile by actively
transporting sodium
into the intercellular
spaces, which causes
water to follow by
osmosis. Cell
morphology changes
dramatically during this
process due to the
osmotic changes
around the cells.
