Histology of the digestive systemreview Anna L Kiss

Histology of the digestive system-review Anna L. Kiss Department of Human Morphology and Developmental Biology Semmelweis University, Budapest 2019

General histology of the digestive tract layers 1. ) Mucosa a. ) l. epithelialis b. ) propria (limphoreticular conn. tissue) c. ) muscularis mucosae (smooth muscle) 2. ) Submucosa: loose connective tissue submucosus plexus (Meissneri): innervation of the a mucosa (villi) lymphatic tissue (lymphocytes, follicles: solitaer) 3. ) T. muscularis: smoothe muscle inner: circular outer: longitudinal myentheric plexus (Auerbach): peristaltic movement 4. ) T. serosa vs. adventitia

Esophagus

Histology of the stomach

Histology of the stomach t. serosa t. muscularis t. submucosa t. mucosa

Histology of the stomach chief cells parietal cells

Histology of the stomach mitochondria parietal cells (EM) intracellular canaliculi+microvilli

Histology of the stomach chief cells: pepszinogen

Histology of the stomach Enteroendocrine cells dense secretory granules in the basal cytoplasm

Histology of the digestive tract Structures increasing the surface: plicae circulares (Kerkring foldes): submucosa villi intestinales: mucosa microvilli (brush border): finger-like projections of the apical plasma membrane of the enterocytes

Plicae circulares (Kerkring redők)

Kerkring foldes The GI tractus wall: 4 concentric layerts: mucosa submucosa muscularis externa (the external muscle layer) adventitia or serosa Z S M P

Villi (Scanning Electron Microscopy) villi Lieberkühn cripts (glands!!)

villi Lieberkhün cripts (intestinal glands) epithelium propria Mucosa muscularis mucosae Submucosa Muscularis Serosa circular longitudinal

microvilli

Lieberkühn cripts Paneth cells: antibacterial enzymes: lysozime

Enteroendocrine cells dividing cells

M (microfold) cells) modifyed enterocytes: antigén presenting cells

Duodenum villusok Brunner glands: alcalic secretum: p. Hshift propria Lieberkühn cripts (glands) muscularis mucosae Brunner glands (submucosa) submucosa

Jejunum muscularis mucosae villi epithelium of the mucosa Kerkring folds mucosa submucosa tunica muscularis + serosa

Ileum villi Peyer plaques (aggregated lymphatic follicles) cripts submucosa muscularis ext. serosa

pl. myentericus (Auerbach)

Mucosa of the colon

Colon: • No villi • deep Lieberkühn cripts • many goblet cells • No Paneth-cells • taeniae • adipose tissue in the submucose and subserose layer • only solitaer lymphatic follicles (folliculi lymphatici solitarii)

Histology of the colon epithelium mucosae tunica muscularis mucosae lamina propria mucosae (+ Lieberkühn krypták) Tela submucosa Tunica muscularis + Serosa Tenia coli

Histology of the colon epithelium mucosae tela submucosa tunica muscularis mucosae

Colon: simple columnar epithelium Junctio anorectalis Transition: stratified columnar or cuboidal epithelium Cutis: stratified keratinized squamouos epithelium Sphincter ani internus Folliculi lymphatici Sphincter ani externus

Portal triad • a v. portae branch (es) • a. hepatica propria branches connective tissue • bile duct • lymph vessels • nerve fibers v. portae branch bile duct a. hepatica branch

Bile canaliculi Neighbouringh surface of the hepatocytes (apical surface): wall of the bile canaliculi: plasma membrae of the hepatocytes!!!) Zonula occludens (tight junction) NO communication between sinusoids and bile canaliculi!!! Interconnecting network. At the periphery: short canaliculi: Hering-canal (epithelium!!!!) stem cells! Bile canaliculi hepatocytes Epekapilláris km (EM) Tight junction

Bile canaliculi

Sinusoidsk • wide capillaries, connect the branches of v. portae ágait with vv. Hepaticae through the central vein • wall: endothelium is not continouos, NO basement membrane (fast exchange between blood and hepatocytes!) • Kupffer-cells: stellate-shaped makrophages (monocyte/makrophage system). • Disse space: between hepatocytes and sinusoids’ endothel. (reticular fibers, collagen type III). • Ito-cells: in space of Disse. (Vitamin A storage, reticular fiber synthesis). Inflammation, cirrhózis: activated, differentiated into myofibroblasts

Kupffer cells

kollagen III: reticular fibbers in the liver (space of Disse)

A májsejt és környezetének sémás rajza cell r. ER glycogen space

Histology of the pancreas Langerhans islands

Histology of the pancreas Ductus intercalaris

Schematic drawings and microphotographs were taken from the following textbook: P. Röhlich (editor): Histology (in Hungarian), Semmelweis Budapest, 2006