Lab activity manual - Histology of the digestive system. Lab activity 1: esophagus stomach - small intestines

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1 Lab activity manual - Histology of the digestive system Jeanne Adiwinata Pawitan Prerequisite: Histology of the 4 basic tissues In this module we learn about the histology of the digestive system, from the esophagus to anus, including the major glands (liver, pancreas, and gall bladder). The lab activity is divided into 2 parts: esophagus, stomach small intestines, and large intestines, anus, liver pancreas gall bladder. In laboratory activity, you have to look at the microscopic appearance of the cells, structures and organs in the digestive system, using a microscope. First look at the whole specimen using low magnification (10x4 or 5X10), then look for the structure/cell that you want to see using higher magnification (10x10, 10x20, 10x40, or 10x45). Lab activity 1: esophagus stomach - small intestines Oesophagus Specimen: Oesophagus cross section Non keratinizing stratified squamous epithelium Lamina propria: (upper part mucous secreting oesophageal cardiac glands) mucosae smooth muscle - longitudinal (towards the stomach very thick) Oesophageal glands (small mucous glands) l plexus of Meissner - myenteric plexus of Auerbach (Upper part skeletal muscle) Lower part smooth muscle Adventitia/serosa - mesothelium Stomach Specimen: oesophagus cardia junction Epithelium: abrupt transition - non keratinizing stratified squamous epithelium simple columnar epithelium (no goblet cell) Cardia: gastric pit (foveola gastrica) moderate (1/4 1/3) Lamina propria Oesophagus: no glands Cardia: cardiac glands tubular, straight/branched, coiled at the base - mucous cells (pale) predominant mucosae: continuous across the junction Oesophagus: small mucous glands Cardia: no glands smooth muscle Oblique (cardia) (oesophagus, cardia) (oesophagus, cardia)

2 Specimen: Fundus/corpus Epithelium: simple columnar epithelium, no goblet cell Gastric pit (foveola gastrica) surface epithelium, shallow (< 1/4) Lamina propria: gastric/fundic glands branched/straight tubular Mucous neck cell Parietal/oxyntic/HCl cell Chief/zymogen/principal cell mucosae (oblique/circular) - from the inner to the outer side: (oblique) - circular (longitudinal) Specimen: Pylorus Epithelium: simple columnar epithelium, no goblet cell gastric pit very deep and wide (>1/2) Lamina propria: pyloric glands tubular, coiled - mucous cells (pale) predominant mucosae: cir long (cir) (from the inner to the outer side: oblique - circular longitudinal) Small intestine Specimen: Gastro-duodenal junction Epithelium Pylorus No goblet cell Lined gastric pit Duodenum With goblet cells Lined intestinal villi plicae (semi)circulares/ valves of Kerckring Pylorus: pyloric glands Duodenum: intestinal glands (crypt of Lieberkühn) mucosae Pylorus: no gland Duodenum: Brünner glands (mucous glands) Oblique: pylorus : pylorus, duodenum, thickened at the gastro-duodenal junction forms pyloric sphincter : (pylorus), duodenum

3 Specimen: Duodenum, jejunum, ileum Epithelium Simple columnar epithelium, goblet cells Lined intestinal villi - plicae (semi)circulares/ valves of Kerckring Lamina propria Intestinal glands (crypt of Lieberkühn) Paneth cells at the base mucosae: cir long (outer) Duodenum: Brünner glands (characteristics) Jejunum: no characteristics Ileum: Peyer s patches (characteristics) Lab activity 2: Large intestine - Liver, pancreas and gall bladder Large intestine Specimen: Appendix small lumen usually full with debris Epithelium: simple columnar epithelium, many goblet cells, no villus Intestinal glands various length, small number Full with diffuse lymphoid tissue and lymph nodules can reach the submucosa mucosae poorly developed: cir long (outer) : occasionally contains lobules of adipose tissue thinner than in colon - continuous Specimen: Colon/caecum Epithelium: simple columnar epithelium, many goblet cells, no villus Intestinal glands deeper than in the small intestines Scattered lymph nodules can reach the submucosa mucosae: cir long (outer) forms 3 longitudinal bands (taenia coli)

4 Specimen: Recto-anal junction at the junction: longitudinal folds = columna rectalis Morgagni (anal/rectal column) Epithelium Rectum: simple columnar epithelium, many goblet cells, lined plicae transversales recti Anal canal anus (the external anal orifice): simple columnar/cuboidal, stratified squamous non keratinized keratinized /dermis Rectum: intestinal glands longer, but fewer than in colon Anal canal anus (the external anal orifice): intestinal glands become shorter and disappear, rectal column, circumanal glands (apocrine), internal hemorrhoidal plexus (veins) - hair follicles, sebaceous glands, external hemorrhoidal plexus mucosae: cir long (outer), become incomplete and disappear at the anal canal merge with lamina propria/dermis at the anal canal smooth muscle thickened at near the end of anal canal internal anal sphincter Rectum smooth muscle - shorter transversal folds (plicae transversales recti) Near the end of anal canal smooth muscle becomes fibroelastic sheet Distal to the internal anal sphincter: external anal sphincter (skeletal muscle) Adventitia Note: Anatomy: the rectal columns meet one another anal valves at the level of pectinate line (abrupt transition from simple cuboidal/columnar to stratified squamous epithelium) Liver Specimen: liver (sus) Classical lobules Central vein Cell sheets, hepatocytes, limiting plate Sinusoids Endothelial cells Kupffer cells Ductules (canal) of Herring Prominent interlobular connective tissue (fibrous connective tissue) Portal area (portal tract, portal canal, portal triad, portal radicle, triangle of Kiernan, Kiernan s space) Branch of portal vein Branch of hepatic artery Bile duct Sublobular vein Specimen: Liver (silver staining) Reticular fibers in Interlobular connective tissue Sinusoid s wall

5 Specimen: Liver (homo) (the same as in liver-sus) Classical liver lobules (no clear border, more difficult to find, so imagine it using the portal area as its edges) Portal area Branch of portal vein Branch of hepatic artery Bile duct Sublobular vein Pancreas Specimen: Pancreas Exocrine portion º Acinus/alveolus Centroacinar cell º Ducts Intercalated ducts Intralobular ducts Interlobular ducts º Connective tissue Intralobular Interlobular Endocrine portion (Langerhans islet) Difficult to differentiate the various cells Capillaries Gall bladder Specimen: Gall bladder º Simple columnar epithelium, no goblet cell lines mucosal folds º Lamina propria Rokitansky-Aschoff sinuses smooth muscle irregularly arranged (long-, transverse, oblique) Adventitia/serosa º Loose/faily dense connective tissue º Mesothelium (serosa) º Aberrant bile ducts (Luschka ducts)