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digestive tract

digestive tract. Diagram of esophagus The longitudinal folds (plica) are the projections formed by mucosa and some CT of submucosa . 1.stratified squamous epithelium 2.lamina propria 3.muscularis mucosae 4. submucosa 5.esophagus gland 6. Muscularis externa 7. Adventitia. 7. 6. 1. 2.

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digestive tract

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  1. digestive tract

  2. Diagram of esophagus The longitudinal folds (plica) are the projections formed by mucosa and some CT of submucosa . 1.stratified squamous epithelium 2.lamina propria 3.muscularis mucosae 4.submucosa 5.esophagus gland 6.Muscularis externa 7.Adventitia 7 6 1 2 5 mucosa 3 4

  3. Esophagus submucosa Esophageal gland Stratified squamous epi. Lamina propria Muscularis mucosae

  4. Lamina propria Muscularis mucosae Stratified squamous epi.

  5. Esophageal gland Lamina propria Muscularis mucosae

  6. 48 Section of fundic stomach, derived from dog, H-E staining The stomach has three histologically recognizable regions: cardiac, fundic, and pyloric.

  7. Lower magnification showing the structure of fundic stomach:1.mucosa： Presents gastric pit (blue arrow), the base of which accept the openings of gastric glands. 1a.simple columnar epithelium： no goblet cells, surface lining or mucous cells 1b.laminar propria： contain fundic gland and a lymph nodule﹡ 1c.muscularis mucosae： 2.submucosa：Loose CT; no glands 3.muscularis externa 4.adventitia：serosa 4 1b 3 1a 2 1c

  8. gastric mucosa a b c submucosa 1.Mucosa contains : a. simple columnar epithelium: composed of surface mucous cells whose cytoplasms poorly stained. b. laminar propria：contain numerous fundic glands c.muscularis mucosae：two layers of inner circular and outer longitudinal smooth muscle cells. 2.submucosa：Loose CT, blood vessles

  9. Simple columnar epithelium Higher magnification: surface mucous cells: produce a mucous substance that coats and protects the stomach's lining from the low pH environment and from autodigestion. Gastric pit Gastric glands The mucosa can clearly shows gastric pit (blue arrow), the base of which accept the opening of gastric gland.

  10. Gastric glands, fundic glands

  11. low power: The lamina propria houses numerous tubular gastric glands, slender BV, and CT, and lymphoid cells. Muscularis mucosa

  12. High power: Although fundic glands are composed of several cell types, only two cell types are readily distinguishable in this preparation. 1.parietal cell：the large cells with various shapes ,the cytoplasm is acidophilic ,red in color，one or two round nuclei located centrally. 2.The chief cells are smaller in size, and columnar in shape with ovoid nuclei basally located and the cytoplasm is basophilic due to the presence of RER. 2 1 1

  13. Identification of three regions of small intestine

  14. duodenum: Lower power： 小肠绒毛 duodenum intestinal villi 小肠腺 intestinal glands duodenal gland 1.intestinal villi are the leaf-like projections co-formed by the epithelium and some CT in laminar propria. 2.laminar propria : many intestinal glands in cross section can be seen. 3.submucosa: containing loose CT and duodenal gland which are mucous glands.

  15. duodenum central lacteal Smooth muscle goblet cells Higher magnification: Villi projections into the lumen is the most diagnostic feature of small intestine structure. The lamina propria core of each consists of loose connective tissue and contains central lacteal and Smooth muscle fibers which run parrell to the axis of the villus core. Covering villi epithelium is a simple columnar epithelium which contains Goblet cells. goblet cells lie between the absorptive cells. They gradually increase in number from the duodenum to the ileum.

  16. Striated border Higher magnification: Villi projections into the lumen is the most diagnostic feature of small intestine structure. The lamina propria core of each consists of loose connective tissue and contains a central, blind-ending lymphatic capillary (often called central lacteal), as well as blood capillaries. Smooth muscle fibers run lengthwise in the villus core. Intestinal villi absorptive cells Smooth muscle Intestinal villus smooth muscle central lacteal Intestinal villus Smooth muscle Goblet cells capillary

  17. Intestinal glands small intestinal gland: is the invagination of epithelium into lamina propria. It is composed of absorptive cell, goblet cell, endocrine cell, stem cell and Peneth cell.

  18. goblet cells Paneth cells of intestinal gland Paneth's cells. Lying in the bases of the intestinal glands, these cells are pyramidal in shape. The most distinctive feature is the presence of many large eosinophilic granules within the apical cytoplasms, which contain the lysozyme, an antibacterial enzyme that may help control the intestinal flora.

  19. duodenal glands Higher power: duodenal glands are mucous tubular glands. Mucous acini are poorly stained. Their nuclei are characteristically condensed and flattened against the basement membrane.

  20. Lower magnification showing the cross section of ileum. The intestinal villi projecting to the lumen and the aggregated lymph nodules can be seen clearly. 1.villi(▲) 2.aggregated lymph nodule ( ) 3.submucosa 4.muscular layer 5.serosa 4 3 1 2 4 5 5

  21. Medium maginifacation showing the aggregated lymph nodules Ileum:villi are short and broad-tipped (club-like), and relatively abundant goblet cells. Its lamina propria typically contains many lymphoid nodule clusters (Peyer's patches). These may be large enough to produce a visible bulge on the luminal surface and extend into the submucosa.

  22. structural feature of colon : a.no villus and no circular rugae b. well-developed large intestinal gland c. contain more goblet cells d. teniae coli: longitudinal bands colon Large intestinal gland mucosa submucosa muscularis serosa

  23. Large intestinal glands The epithelium is simple columnar with a great abundance of goblet cells. The mucosa has many deep crypts (large intestinal glands), containing abundant goblet cells and few absorptive cells. The lamina propria has more lymphoid cells and nodules than does that of the small intestine.

  24. appendix lymph nodule Medium power: appendix The most characteristic feature of the appendix is the presence of masses of lymphoid tissue in the mucosa and submucosa. Note that the mucosal glands are much less closely packed than elsewhere in large intestine. As seen in figure, the lymphoid tissue also forms lymph nodules often containing germinal centres. The submucosa also contains many adipose tissue. The muscularis externa is covered by serosa.

  25. Observing slides(观察玻片): • 1. Esophagus HE NO. 47 (食管 HE 47号） • 2. stomach HE NO.48 (胃 HE 48号) • 2. duodenum HE NO.50 (十二指肠 HE 50号) • 3. jejunum HE NO.51 (空肠 HE 51号) • 4. illeum HE NO.52 (回肠 HE 52号) • 5. colon HE NO.53 (结肠 HE 53号) • 6. appendix HE NO.54 (阑尾 HE 54号) • Draw part of gastric mucosa with low power (10×）

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