1. Digestive glands

2. General outline • small digestive glands • distributed in the wall of digestive tract • esophageal glands, gastric glands and • intestine glands • large digestive glands • outside the wall of digestive tract • salivary glands, liver and pancreas

3. Large salivary glands • Include parotid, submandibular and sublingual glands • are compound tubuloacinar glands • are composed of acini and ducts

4. Acinus : • acinar epithelium: simple cuboidal or pyramidal cells • myoepithelial cell • basal membrane Structure: Serous acini Mucous acini Mixedacini Be divided into

5. Serous acini • cytoplasma are deep stained • nucleus are spherical in shape and near the base • secretion is thin, contains salivary amylase and a little mucus

6. Serous acini and striated duct

7. Mucous acini • cytoplasma are light-blue stained • nucleus are flattened ovoid shaped and close to the base • secretion is thick; contains mucoprotein

8. Mucous acini

9. Mixedacini • consist of above two kinds of cells • demilunes: several serous cells are attached eccentrically to the mucous acini

10. Mixed acini

11. Ducts: • Intercalated ducts diameter: thinnest wall: simple low cuboidal epithelium

12. Striated duct (secretory duct) • wall: simple columnar epithelium; the nucleus is near the cell apex; cytoplasm is acidpphilic; has basal striations • EM: the basal striations created by membrane infolding and mitochondia • reabsorbing sodium and excreting potassium; transport water and ions

13. Intercalated ducts and striated ducts

14. Interlobular duct Wall: pseudostratified epithelium • Main duct Near its orifice become stratified squamous epithelium

15. Parotid gland • pure serous gland • longer intercalated duct • secrete 25% of saliva, more salivary amylase, less mucus

16. Parotid gland

17. Submandibular gland • mixed gland. Serous acini are more than mixed or mucous acini • short intercalated duct, longer striated duct • secrete 70% of saliva, less salivary amylase, more mucus

18. Submandibular gland

19. Sublingual gland • mixed gland, mucous and mixed acini predominant, more demilune • without intercalated duct, obscure striated duct • secrete 5% of saliva, most mucus

20. Sublingual gland

21. Pancreas Exocrine portion: • the features of the acini • a single layer of pyramidal serous cells surrounded by basal lamina, without myoepithelial cells • centro-acinar cells: the epithelial cells of intercalated duct penetrating into the lumen of the acinus

22. the feature of ducts • the intercalated duct is long and has branches • no striated duct • main duct: lined by simple columnar epithelium in which a few goblet cells and endocrine cells can be seen

23. The functions of exocrine portion Secret abundant trypsinogen, chymotrypsinogen, amylase, lipase, sodium bicarbonate and trypsin inhibitor

24. Pancreas

26. Pancreas ( show centro-acinar cells and intercalated ducts)

27. Endocrine portion (pancreatic islet): • rounded clusters of cells embedded within exocrine pancreatic tissue • are divided into three kinds of cells: A, B, and D cells • fenestrated capillaries are among the cells

28. Pancreas (show pancreatic islet)

29. Endocrine portion PP cells: pancreatic polypeptide G cells: gastrin Other cells

30. A cells B cells D cells

31. Liver Hepatic plates Sinusoid Central vein Liver lobule Interlobular arteries Interlobular veins Interlobular bile ducts Portal area

33. Functions of liver: • bile secretion • synthesize: protein, glycogen, cholesterin • detoxification and inactivation • defence • hemopoiesis

34. Human liver Pork liver

35. Liver lobule: • hepatic plates: are composed of a single layer of hepatocytes arranged in radial • sinusoid: situated between the hepatic plates, forming a complex network • central vein: occupies the centre of the liver lobule

36. Liver lobule

38. Hepatic plates

39. Hepatic cords and liver sinusoids

40. Hepatocytes • polyhedral in shape, eosinophilic cytoplasm, one or two large rounded nuclei with one or 2 typical nucleoli • EM: Mi, RER, SER, Golgi apparatus, lysosomes, microbodies, inclusions

41. Mitochondria provide the energy for the hepatocytes • Rough endoplasmic reticulum synthesize some plasma proteins • Golgi apparatus participate in the formation of bile and lipoprotein

42. Smooth endoplasmic reticulum • synthesize bile, triglyceride and LDL • metabolism of the lipid, hormones and cholerythrin • inactivate steroid hormone • biotransformation of some materials • detoxification of noxious substances

43. Lysosomes • actively participate the metabolism of hepatocyte and renewal of organelles • play a role in metabolism and transport of cholerythrin • storage of iron

44. Microbodies detoxification: catalase and peroxidase; reduce the hydrogen peroxide into H2O • Inclusions include glycogen, lipid droplets, pigment etc; These contents vary according to physiologic state of human body

45. Bile canaliculi • between two adjacent hepatocytes • the membrane of hepatocyte projects to the lumen, forming many microvilli • the cell membranes near the bile canaliculi are firmly bound by junctional complexes

46. Bile canaliculi

47. Liver sinusoid • spaces between the hepatic plates • irregular in shape • composed of only one discontinuous layer of fenestrated endothelial cells, no diaphragm, no basement membrane • Kupffer cells are located within the sinusoid cavities

48. Kuffer cells in liver sinusoid

49. Liver sinusoid and space of Disse

50. Space of Disse • separates the endothelium from the hepatocytes • contains some reticular fibers and fat-storing cells