BILIARY PASSAGES &

Objectives:es: The student should be able to identify ◧ Editing file & describe the histological features of: ◧ Important 1. Intrahepatic biliary passages. ◧ Doctor notes / Extra 2. Extrahepatic bile ducts. 3. Gall bladder. 4. Exocrine pancreas.

438 Histology Team GNT Block Biliary Passages

Intrahepatic passages: 1- Bile canaliculi.

2- Bile ductules (canals of Hering).

3- Interlobular bile ducts.

Extrahepatic passages: 4- Right & left Hepatic ducts.

5- .

6- Common .

438 Histology Team – GNT Block 2 Intrahepatic passages

Bile Canaliculi Bile Ductules (Canals of Hering) Interlobular Bile Ducts

• Narrow channels located between • Near the peripheral portal areas, • Are in the portal areas. , limited only (& formed) bile canaliculi empty into bile • Lined by simple cuboidal by the cell membranes of 2 ductules composed of cuboidal epithelium (becomes simple hepatocytes. epithelial cells called columnar epithelium near the • They are the first portions of the cholangiocytes. ). bile duct system. • After a short distance, these • Interlobular bile ducts merge to • Microvilli project from the ductules collect and end in the form larger ducts, which eventually into the bile canaliculi, thus increasing interlobular bile ducts in the unite to form the right and left the surface area. portal areas hepatic ducts. • Tight junctions between the cell membranes of the 2 hepatocytes prevent leakage of bile.

438 Histology Team – GNT Block 3 Extrahepatic passages:

Right & left Hepatic ducts. Common Hepatic Duct .

Formed by union of the right & left hepatic ducts. It joins the , arising from the , forming the common bile duct. Similar in structure to the wall of gallbladder and other extrahepatic bile ducts. • Mucosa: ( no muscularis mucosae & submucosa ) - Epithelium: Simple columnar. - Lamina propria. • Muscularis: bundles of smooth muscle fibers in all directions. • Adventitia.

438 Histology Team – GNT Block 4 ❏ Gallbladder A saclike structure that stores, concentrates and releases bile Its wall is formed of: Mucosa: highly folded. - Simple columnar epithelium. - Lamina propria: contains mucous glands in the neck of gallbladder. Muscularis: bundles of smooth muscle fibers oriented in all directions. Serosa or adventitia.

❏ Pancreas Stroma: capsule, septa & reticular fibers. Parenchyma: Pancreas is a mixed gland: Exocrine part (acini & ducts): produces digestive pancreatic enzymes. Endocrine part (islets of Langerhans): produces hormones.

438 Histology Team – GNT Block 5 Exocrine Pancreas

Pancreatic Acini Pancreatic Acinar Cells Duct System:

• They are serous acini: secreting a • Pyramidal in shape. • Centroacinar cells.(flat cells) thin fluid rich in digestive pancreatic • Nuclei are basal. • Intercalated ducts (low cuboidal). enzymes. • Cytoplasm: • Intralobular ducts (NOT prominent). • Centroacinar cells: • Basal part basophilic (due to • Interlobular ducts. Their nuclei appear in the center of abundant rER). • Main . the acini. They represent the • Apical part acidophilic (due to beginning of the ducts. secretory granules). • No myoepithelial cells around the acini. (Stimulated by stomach hormones (hormonal Not neuronal))

438 Histology Team – GNT Block 6 Parotid gland

intralobular duct = striated duct

Pancreas

islets of Langerhans

Under microscope we can differentiate Between parotid gland and pancreas by : • prominent intralobular duct (in parotid gland) • islets of Langerhans (in pancreas only)

438 Histology Team – GNT Block 7 Quiz

1- What is the lining epithelium of the 4- Which one of the following is lined by simple gallbladder? columnar epithelium. A. Simple columnar A. Bile Ductules B. Simple cuboidal B. Common bile duct. C. Simple squamous C. Interlobular Bile Ducts D. Transitional epithelium D. A & B

2- Which one of the following is Formed 5- Which cells are not found in the pancreatic by union of the right & left hepatic ducts: acini? A. Interlobular bile ducts. A. Centroacinar cells B. Common bile duct. B. Serous cells C. Common Hepatic Duct C. Myoepithelial cells D. Right bile duct

3- Which of the following is true about Bile 6- the Basal part of Pancreatic Acinar Cells is Ductules basophilic due to A. end in the intralobular bile ducts A. due to abundant rER B. composed of columnar epithelial B. due to abundant sER C. empty into bile canaliculi. C. due to secretory granules D. end in the interlobular bile ducts D. due to myoepithelial cells

1.A 2.C 3.D 4.B 5.C 6.A 5.C 4.B 3.D 2.C 1.A 8

Team Leaders

❏ Abdullah shadid ❏ Sarah alflaij

Good luck

438 Histology Team – GNT Block 9