Gastrointestinal

• Esophagus-compare to vagina, has stratified squamous non-keratinized epithelium with esophageal glands (duh). The muscularis externa contains either skeletal, smooth, or a mixtures of both types of muscle depending upon where the cross-section is made

• Stomach-simple columnar epithelium that is all mucous secreting therefore is does not have goblet cells. It also has three layers of muscularis externa and a large area of gastric glands. Magnify the area of the gastric glands and you will find the different cells types. *Parietal cell – pink, secretes HCL and intrinsic factor. *Chief cell – blue, makes pepsinogen. If you can’t remember which cell is which, just remember that the chief cells have a “manly” name and are therefore blue!
  Make sure you know the layers in all slides of the GI tract i.e. Lamina propria, muscularis mucosae, submucosa and muscularis externa. Also, if he wants you to ID a cell type within the lamina propria it is most likely a lymphocyte or plasma cell (black dots). If you see any white spaces that form lines within the lamina propria/villi it is probably a lacteal (small lymphatic vessel)
  Don’t forget about the Myenterric or Auerbach’s Plexus which is the parasympathetic ganglia located in between the inner circular and outer longitudinal muscle layers of the muscularis externa throughout the GI tract.

• Duodenum ID by the *Brunner’s glands which secrete an alkali mucous, it also has villi and plica circularis with normal GI epithelium (simple columnar with goblet cells and brush border)

• Jejunum-*no Brunner’s glands, also has longer plicae. Don’t forget about good old *Paneth Cells that have the bright red granules and secrete lysozyme.

• Ileum-shorter plicae, many more goblet cells, peyers patches (lymphatic nodules that don’t have the normal GI tract epithelium over them. They instead have the M cells)

• Colon no villi, many more goblet cells

• Gallbladder ID by the really weird projections on the surface, also has simple columnar epithelium, no brush border etc.

• Parotid gland-only serous units

• Submandibular – mixed but predominantly serous

• Sublingual-mixed but predominantly mucous

• Don’t forget about ******Serous Demilune!!!!!!!!!

• Liver-unless he uses the pig liver, you will not really see the classic lobule etc. ID by the central vein and the unique appearance of the hepatocyte cells. Different from spleen and pancreas because it all essentially one color. Also, no lymphatic nodules in the liver. Don’t forget about the triad found at the corners of the liver lobule -hepatic artery, portal vein and bile duct

• Pancreas – looks like undercooked steak, has areas of lighter pink coloring which are the islets of Langerhan’s (endocrine). Red areas in between is the exocrine portion. ID this organ by its coloration also, no lymphatic nodules.

Category: Anatomy Notes