For medical, nursing and physiotherapy undergraduates, and postgraduates

1. DIGESTIVE SYSTEM - 4
Liver, Pancreas and
Gall Bladder

2. COMPONENTS
• Oral cavity
• Pharynx
• Esophagus
• Stomach
• Small intestine :
• Duodenum
• Jejunum
• Ileum
• Large intestine
• Appendix
• Rectum
• Anal canal
• Salivary glands
• Liver
• Pancreas
• Gall bladder

3. ACCESSORY ORGANS
• Accessory organs are located outside the digestive tube. Excretory
ducts from the salivary glands open into the oral cavity.
• Liver, gall bladder and pancreas deliver their secretory products to the
small intestine by excretory ducts.

4. LIVER – FUNCTION
• Liver is located strategically. All the nutrients and liquids absorbed
in the intestine enter the liver through hepatic portal vein except
complex lipid products which are transported through lymph
vessels.
• The nutrients percolate through the hepatic sinusoids. Nutrient
rich oxygenated blood reenters general circulation.

5. LIVER – STRUCTURE
• Glisson’s capsule encloses the entire organ and extends into its
interior as numerous septa and trabeculae.
• Liver exhibits repeating hexagonal units called Hepatic Lobules.
• From the hilum, connective tissue septa extends between the hepatic
lobes as Interlobular septa and define a hepatic lobule.

6. LIVER - STRUCTURE
• It is composed of:
• Parenchyma cells (hepatocytes)
• Connective tissue stroma
• Sinusoids
• Bile canaliculi
• Numerous portal triads
• Tributaries of hepatic veins

11. CLASSICAL HEPATIC LOBULE
• It consists of hexagonal mass of liver cells
• Central axis of the lobule is occupied by Central vein, tributary of
hepatic vein.
• Portal triads: Also called as Portal canals, Portal area or Portal tract.
Covered by Glisson’s capsule and found in interlobular spaces at the
meeting place of three adjacent lobules.

13. CLASSICAL HEPATIC LOBULE
• From the central vein, hepatocytes radiate outwards as sheets or
plates of cells (of about 20) – Hepatic laminae
• Hepatic laminae - One cell thick, branching, perforating and irregular.
• Limiting plate: present numerous perforations for inlet venules and
radicles of artery
• Hepatic Lacunae: Spaces between the laminae occupied by sinusoids

15. PORTAL TRIAD / PORTAL AREA
• It is collection present in interlobular
septa of :
1. Interlobular branch of Hepatic artery
2. Interlobular branch of Portal vein
3. Interlobular branch of Bile duct
• Also may be found lymphatic
vessels.

19. HEPATIC SINUSOID
• Tortuous, dilated blood channels lined by a discontinuous layer of
fenestrated endothelial cells.
• Endothelial cells also exhibit fenestrations and discontinuous basal lamina.
• The hepatic sinusoids are separated from the underlying hepatocytes by a
subendothelial perisinusoidal space (of Disse)
• Kupffer cells: Macrophages present on the luminal surface of the
endothelial cells

21. HEPATIC SINUSOIDS

23. CLASSICAL HEPATIC LOBULE
• Inlet venules from transverse terminal Portal vein perforate limiting
plate and enter into sinusoids.
• Radicles of hepatic artery perforate LP and either join inlet venules or
open directly into sinusoids.
• Blood of sinusoids drain into central vein
• Central veins from adjoining lobules join to form Inter-lobular vein
• The later unite as Hepatic vein – Inferior Vena cava.

25. CLASSICAL HEPATIC LOBULE
• Interlobular vessels and ducts are highly branched in liver. Hence,
more than one section of these structures are seen in portal area.

26. BILE CANALICULI
• These are tiny channels between individual hepatic cells in the
hepatic plates.
• They follow an irregular course between the hepatic plates and
branch freely, finally converge at the periphery of liver lobules in the
portal area as bile ducts.

28. KUPFFER CELL
• Majority of cells lining the sinusoids are Epithelial cells
• Stellate shaped cells with attenuated cytoplasm and small nucleus.
• Macrophage cells derived from Mononuclear phagocyte system
(MPS)
• Located on luminal side of the epithelial cells
• Indian ink preparation – large cells with several processes with
irregular or stellate outline that protrude into sinusoids.

30. GLYCOGEN GRANULES
• Cytoplasm of liver cells varies in appearance depending on
nutritional status.
• Hepatocytes store large amounts of glycogen after meal in their
cytoplasm
• Periodic acid Schiff stain: Glycogen granules stain bright red and
exhibit irregular distribution within the cytoplasm

32. RETICULAR FIBERS
• Fine reticular fibers provide most of the supporting connective tissue
of liver.
• Reticulin stain: Reticulin fibers stain black and liver cells stain pink or
violet.
• Reticulin fibers are seen lining the:
• Sinusoids
• Support epithelial cells
• Form dense network of reticula fibers in the wall of central vein
• Interlobular system along with collagen fibers

35. GALL BLADDER

36. GALL BLADDER – HISTOLOGIC FEATURES
• Gall bladder wall exhibits following layers:
• Mucosa
• Muscularis layer
• Adventitia / Serosa

37. MUCOSA
• Mucous membrane shows temporary folds
• Epithelium – Simple columnar epithelium with striated border
• Crypts or diverticula seen. They resemble tubular glands but there
are no glands in gall bladder. Absent goblet cells.
• Lamina propria – loose connective tissue
i. Diffuse lymphatic tissue
ii. Blood vessels
iii. Numerous plasma cells
iv. Rokistansky- aschoff sinuses

38. MUCOSA
• Fibromuscular coat:
• Bundles of randomly oriented smooth muscle fibers
• Do not show distinct layers
• Interlacing elastic fibers
• Numerous connective tissue
• Serosa / Adventitia: Thick layer of dense connective tissue with
• Blood vessels
• Lymphatics
• Nerves
• Absent Goblet cells, Villi, Muscularis mucosae and Submucosa.

42. PANCREAS

43. HISTOLOGY FEATURES
• Both exocrine and endocrine components present. Exocrine
component predominates.
• Closely packed serous acini and zymogenic cells arranged in small
lobules
• The lobules are separated by thin, intralobular and interlobular
connective tissue septa.
• Interlobular connective septa contains:
i. Blood vessels
ii. Interlobular ducts
iii. Sensory receptor –Pacinian corpuscle

44. PANCREATIC ACINUS
• Consists of pyramid shaped, protein secreting zymogenic cells
surrounding a small lumen.
• The excretory ducts of individual acini are visible as Centro-acinar
cells
• Intercalated ducts, interlobular ducts are seen located in interlobular
connective tissue septa.
• Isolated pancreatic islets of Langerhans are seen within the serous
acini.

46. ISLETS OF LANGERHANS
• Isolated pancreatic islets of Langerhans (pale staining) are demarcated
from the surrounding exocrine acini tissue by a thin layer of reticular fibers.
• The islets are larger than the serous acini. They are arranged in cords and
compact clusters, between which are found connective tissue fibers and a
capillary network.
• A thin connective tissue capsule separates both the exocrine and endocrine
parts.

50. SUMMARY