Gastrointestinal tract II. Histology and embryology

Digestive tube  Esophagus  Ventricle - gaster  Small intestine  Large intestine  Rectum  Anus

Esophagus –stratified squamous nonkeratinising epithelium –lamina propria mucosae – distally esophageal cardial glands –in submucosis mucinous glands - gl. oesophagicae –proximally skeletal musculature –adventitia – serosa only in short abdominal part

Slide – Esophagus HE

Gaster  tunica mucosa –areae gastricae  foveolae gastricae –simple columnar epi - mucous production –lamina propria mucosae gastrical glands, lymphatic follicles  tunica muscularis –inner - fibrae obliquae –medial - circular - m. sphincter pylori –outer - longitudinal

Tunica mucosa of gaster  gastric pits deeper in pyloric part glands enter these pits –gl. cardiacae - deep –gl. gastricae propriae –gl. pyloricae - shallow

Gastric cells  main cells- pepsinogen, lipase  parietal cells- HCl, intrinsic factor abundant intracellular channels  mucinous cells – mucous  enteroendocrine cells - gastrin, somatostatin  undiferentiated cells - mitotically active

Synthesis of HCl  in parietal cells  Cl - - from plasma  H + - from H 2 CO 3 –by carboanhydrase from CO 2 and H 2 O

Slide – Cardia of gaster HE

Slide – Fundus of gaster HE

Intestinum tenue (= small intestine)  duodenum  jejunum  ileum mesenterium - radix mesenterii plicae circulares, villi intestinales

Tunica mucosa of small int.  plicae circulares (Kerkringi)  villi  Crypts of Lieberkühn  simple columnar epithelium  lamina propria mucosae –vessels, smooth muscles, lymph. foll.

Cells of small int. mucosa  enterocytes - resorption –microvilli, interdigitations, lipid droplets  goblet cells – mucus production  Paneth cells – lysozym production  endocrine cells - 12 types –cholecystokinin, sekretin  M-cells - over Peyer‘s plates (later)  undiferentiated cells

Villi  digit- to leaf-formed elements  about 10times surface enlargement  surface – enterocytes, goblet cells  smooth muscle „skeleton“  lot of capillaries  lymphatic, so called lacteal vessels

Other layers of small int. wall  Tela submucosa –in duodenum – glands of Brunner tuboalveolar mucinous alkalic secretion –mainly in ileum – Peyer‘s plates acumulation of lymphatic tissue  other layer correnspond to standard form of git tube

Slide – Pylorus – duodenum HE

Slide – Duodenum HE

Slide – Small intestine HE

Mucosa of large intestine  no folds and villi  crypts of Lieberkühn are deeper –enterocytes – less of microvilli –goblet cells are numerous –Paneth cells are missing –endocrine cells are present

Other layers of large intestine wall  tunica muscularis externa –inner circular - haustrations –outer longitudinal – reduced to taenie coli  tunica serosa –appendices epiploicae – adipous tissue

Slide – Colon HE

Appendix vermiformis  Paneth cells are present  lamina propria mucosae –fulfilled with lymphatic tissue = noduli lymphoidei aggregati („tonsilla abdominalis“)  longitudinal musculature surrounds it completely – no taenie

Slide – Appendix vermiformis HE

Intestinum rectum  pars pelvina –plicae transversales recti - semilunar –contains circular muscle layer  canalis analis –zona haemorrhoidalis - m. sphincter ani int. columnae anales (6-10) change of epithelium – stratified squamous nonkeratinising anal plexus – cavernous body –zona cutanea – keratinising epithelium glandulae circumanales (sweat and apocrine)