Biol 432 pp digestive glands

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.