Digestive Glands

Digestive Glands Li Jinru (Jennifer) Department of Histology and Embryology

1 Salivary Glands

Salivary Glands • Compound tubuloacinar glands – Acini • Glandular Cells • Myoepithelial Cells • Basement Membrane – Ducts

Salivary Glands • 1.1 Acini – Serous Acinus – Mucous Acinus – Mixed Acinus

Salivary Glands • 1.1.1 Serous acinus • serous secretory cells – L.M.:

• round nucleus • acidophilic zymogen granules – Function:

• to secrete serous

Salivary Glands • 1.1.2 Mucous acinus • mucous secretory cells – L.M.:

• flattened nucleus • large mucinogen granules – F:

• to secrete mucous

Salivary Glands • 1.1.3 Mixed Acinus • two types of secretory cells – Demilune—a small group of serous cells arranged in a half-moon fashion and attached on one side of a mucous acinus – Function: • to secrete mucous and serous

Salivary Glands • 1.2 Ducts – – – – –

Intercalated ducts Striated ducts (Secretory ducts) Interlobular ducts Lobar ducts Major excretory duct

Striated duct

Serous cell

Intercalated duct

Mucous cell

Demilune Striated duct

Salivary Glands • Parotids • Submandibular glands • Sublingual glands

Pancreas

Pancreas • Exocrine Portion – Acini: Serous acini • No myoepithelial cells • Centroacinar cells • F: To secrete pancreatic juice. – Ducts Intercalated ducts → Intralobular ducts → Interlobular ducts → Pancreatic ducts →Duodenal lumen

Pancreas • Endocrine Portion-Pancreatic Islets – – – –

small clusters of endocrine cells scattered among the exocrine acini rich in fenestrated capillaries consists of four different cell-types

Serous acinus

Pancreas islet Capillary

Pancreas • A-cells (20%) —located at the periphery F: To secrete glucagon • B-cells (75%) —located near the center F: To secrete insulin • D-cells (5%) F: To secrete somatostatin • PP-cells F: To secrete pancreatic polypeptide

Liver

Liver • Hepatic Lobule – basic unit of liver – a polygonal prism

Liver • Composition: – – – – –

A central vein Hepatocytes→ hepatic plates Hepatic sinusoids Perisinusoidal space (Space of Disse) Bile canaliculi

Liver • Central Vein – the smallest branch of the portal vein – Its endothelial cells are continuous with adjacent sinusoids

Liver • Hepatic Plates – be consists of a row of closely-packed hepatocytes – be anastomosed and radiate from the central vein – there are some pores

Liver • Hepatocytes – L.M.: • polygonal cell • spherical nucleus • cytoplasm is acidophilic

Liver • E.M.: – Mitochondria – Golgi complexes – RER and free ribosomes – SER – Lysosomes – Microbodies – Inclusions

Liver • Hepatocytes have 3 kinds of surfaces – The surface adjacent to a sinusoid – The surface of adjacent cells – The surface facing the bile canaliculus

Liver • Hepatic Sinusoids – form an extensive sponge-like structure. – irregular – lined by endothelial cells and Kupffer cells. • Kupffer cells – Scattered; – Function: Phagocytose remnants of degenerating erythrocytes

Liver • Perisinusoidal Space (Space of Disse) – It’s an space between the endothelial cells of the sinusoid and the hepatocytes. – Metabolic exchanges between the liver and the blood occur here.

• Bile Canaliculi – be formed by the indented plasmalemmas of opposing cells. – tight junctions (Hepatitis→Icterus)

Liver • Portal Areas – In the angles where adjacent hepatic lobules meet – the interlobular arteries – the interlobular veins – the interlobular bile ducts

Liver Portal vein →Interlobular veins → Hepatic sinusoids Hepatic artery →Interlobular arteries ↓ Hepatic vein ← Sublobular veins ← Central veins Hepatic ducts ←Interlobular bile ducts ←Bile canaliculi