Embryology: Development of digestive system • image556 Trávící systém II - 33 · Embryo folding – incorporation of endoderm to form primitive gut. · Outside of embryo – yolk sac and allantois. · Vitelline duct Trávící systém II - 34 Stomodeum (primitive mouth) ð the oral cavity + the salivary glands Proctodeum ð primitive anal pit Primitive gut ð whole digestive tube + accessory glands Proctodeum Trávící systém III - 22 pharynx forgut midgut hindgut •The epithelium of gut and glandular cells of associated glands of the gastrointestinal tract develop from endoderm •The connective tissue, muscle tissue and mesothelium derive from splanchnic mesoderm •The enteric nervous system develops from neural crest primitive gut foregut midgut hindgut from above ductus to cloacal pharyngeal omphalomesentericus membrane membrane and yolk sack st11oralm stage11cloacal Pharyngeal membrane Derivatives of forgut – pharynx, esophagus (+ respiratory diverticle), stomach, cranial part of duodenum midgut – caudal part of duodenum (+ liver, gall bladder, pancreas), small intestine and part of large intestine (to the flexura coli sin.) hindgut – large intestine (from flexura coli sin.), rectum, upper part of canalis analis Oral cavity •primitive mouth pit – stomodeum •lined with ectoderm •surrounded by: - processus frontalis (single) - proc. maxillares (paired) - proc. mandibulares (paired) •pharyngeal membrane (it ruptures during the 4th week, primitive gut communicates with amnionic cavity) • File:Gray44.png 002f Pharyngeal (branchial) apparatus •Pharyngeal arches • appear in weeks 4 - 5 •on the ventral side of the pharyngeal gut. •each arch = cartilage, nerve, aortic arch artery and muscle •pharyngeal clefts and pouches are located between the arches •membrana obturans parL5001 Pharyngeal arches Pharyngeal pouches Pharyngeal clefts - 4 weeks, PowerPoint Templates, Images, Diagrams, Slides ectoderm endoderm membrana obturans http://www.vesalius.com/graphics/cf_storyboards/branchial_cyst/embG5103.jpg http://www.vesalius.com/graphics/cf_storyboards/branchial_cyst/embG5104.jpg Ectodermal pharyngeal clefts (grooves) Endodermal pharyngeal pouches Early+development+of+the+pharyngeal+grooves+and+pouches Fate of pharyngeal pouches and clefts early later Sinus cervicalis + tympanic cavity Tympanic nenbrane F14 membrana obturans ectoderm endoderm Structures derived from Arches ARCH Nerve Muscles Skeletal Structures Ligaments 1 (maxillary/mandibular) trigeminal (V) malleus, incus ant lig of malleus, sphenomandibular ligament 2 (hyoid) facial (VII) stapes, styloid process, lesser cornu of hyoid, upper part of body of hyoid bone stylohyoid ligament 3 glossopharyngeal (IX) greater cornu of hyoid, lower part of body of hyoid bone 4 & 6 superior laryngeal and recurrent laryngeal branch of vagus (X) thyroid, cricoid, arytenoid, corniculate and cuneform cartilages Structures derived from Pouches Each pouch is lined with endoderm and generates specific structures. POUCH Overall Structure Specific Structures 1 tubotympanic recess tympanic membrane, tympanic cavity, mastoid antrum, auditory tube 2 intratonsillar cleft crypts of palatine tonsil, lymphatic nodules of palatine tonsil 3 inferior parathyroid gland, thymus 4 superior parathyroid gland, ultimobranchial body parL5001 primitive pharynx thyroid gl. laryngotracheal diverticle (respiratory divertcle) 250px-Development esophagus Esophagus development below respiratory diverticle, behind larynx and trachea Esophagus development • •differentiation of epithelium from endoderm •during the 2nd month endoderm proliferates and temporarily closes esophageal lumen •other tissues and structures in the wall arrise from splanchnic mesoderm 950 mesoesophageum dorsale gives rise to dorsal mediastinum and mediastinal pleura mesoesophageum ventrale disappears esophagus Mesenteries – suspensory duplicature derived from mesoderm and mesenchyme (a fold of tissue that attaches organs to the body wall) mesooesophageum dorsal wall of body Trávící systém II - 36 · in the 4th week – spindle dilatation of distal forgut · endoderm – epithelium and glandular cells · splanchnic mesoderm – other tissues of stomach wall Stomach development Trávící systém II - 36 Rotation around longitudinal axis: - left side → ventrally, - right side → dorsally. Uneven growth of ventral and dorsal wall: - curvatura minor (to the right), - curvatura major (to the left). Rotation around sagital axis : - curvatura minor (cranial position), - curvatura major (caudal position). Trávící systém II - 37 Sagital rotation axis Image:Gray983.png The liver bud (hepatocystic diverticle) appears at the distal end of the foregut (week 4) and divides into hepatic and cystic diverticles, later ventral pancreatic bud and dorsal pancreatic bud (week 5). Both pancreatic buds meet and fuse (week 6). Trávící systém II - 40 Trávící systém II - 41 Trávící systém II - 42 liver The midgut is divided into two regions at the viteline duct: the cranial and caudal limbs. The derivatives of the cranial limb - the distal duodenum, jejunum, and proximal ileum. The derivatives of the caudal limb - the distal ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon. the midgut grows faster than that of the embryo, creating: - duodenal loop - umbilical loop Midgut Trávící systém II - 43 Duodenal loop and umbilical loop Umbilical loop herniates into the umbilical cord (physiologic herniation, in week 6-10) Flexura duodenojejunalis forgut midgut Duodenum development • • •Duodenal loop – 2 limbs: upper limb (from forgut) lower limb (from midgut) •On top of loop – diverticles (for liver, gallbladder, pancreas) • • • Trávící systém III - 38 Pancreas rotation cartoon Due to rotation of umbilical loop, duodenal loop changes its position (from front to the right) and becomes retroperitoneal organ (together with pancreas) Intestines development •Umbilical loop – 2 limbs: cranial – jejunoileal limb (jejunum, major part of ileum) caudal – ileocecal limb (rest of ileum, caecum + appendix, colon ascendens and 2/3 of colon transversum) •A. mesenterica sup. – axis of rotation •week 6 – physiologic herniation into the umbilical cord, week 10 – reposition into abdominal cavity • L13I7 Trávící systém II - 44 loadBinaryCA3S4KPL 90º 180º after 270º rotation -In the umbilical cord, the midgut loop rotates 90° counter-clockwise around the axis of the superior mesenteric artery. -Upon returning, the gut undergoes another 180° counter-clockwise rotation, placing the cecum and appendix near the right lobe of the liver. -The total rotation of the gut is 270°. The distal end of the hindgut – the cloaca. Derivatives of the hindgut: the distal 1/3 of the transverse colon, descending colon, sigmoid colon, rectum and upper part of anal canal (above the pectinate line). Hindgut Trávící systém II - 45 Rectum L13I9 Division of the cloaca - urorectal septum divides the cloaca into a ventral urogenital sinus and a dorsal anorectal canal. The cloacal membrane breaks down during the 7th week. Distal to the pectinate line (site of the former cloacal membrane), the epithelium of the anal canal derives from ectoderm of proctodeum (primitive anal pit) Mesenteries •double layer of peritoneum enclosing organs and connecting them to the body wall image985 Ventral mesentery exists only in region of distal part of esophagus, stomach (lesser omentum) and upper part of duodenum Dorsal mesentery forms dorsal meso- gastrium (greater omentum), dorsal mesoduodenum, mesentery proper (jejunum, ileum) Stomodeum and face development •During the 2nd month i.u. •Stomodeum •Mesenchymal processes covered with ectoderm - processus frontonasalis - processus mandibulares - processus maxillares vývoj_obl5t kopie Frontal view of an embryo at 4 to 5 weeks of age. Observe the branchial arch formation and the ruptured buccopharyngeal membrane. Frontal+view+of+an+embryo+at+4+to+5+weeks+of+age I - II - III - (perforated) Processus nasalis (lat. and med.) Processus frontalis Processus maxillaris Processus mandibularis (mandibular arch) image562 Development of the tongue (from pharyngeal arches) Developing+face Developing face week 4 4-5 5 -6 6-7 nasolacrimal groof Mandib. Maxill. Frontonasal Facial processes: Nasal lat. + med. Intermaxillary segment intermaxsegm •Palate development • 3 ectoderm-mezenchymal plates: •a) medial palatine plate (1) – from processus nasalis medialis (intermaxillare) ð primary palate •b) lateral palatine plates (2) – from medial side of maxillary processes ð secondary palate intermaxsegm palate Foramen incisivum Raphe palati vyvoj patrac vyvoj patraa vyvoj patrab Clefts of maxilla and palate Cleft between lateral incisivus and caninus Cheilo-gnatho-palato-schisis unilateralis or bilateralis n intermaxsegm patro_rozstepy Foramen incisivum cheilo – gnatho – palatoschisis 1: 2500, heredity- autosomal dominant rozstepypatra • • • Clefts of primary palate Ventrally from foramen incisivum One or both lateral plates don‘t fuse with primary palate primpatro_rozštepy kopie Clefts of secondary and primary palates Ventrally and dorsally from foramen incisivum Lateral palatine plates are not fused with primary palate Nasal septum is free if lateral plates are not fused (raphe palati is absent) Clefts of secondary palate (palatoschisis) behind foramen incisivum Nonfused palatine plate in middle plane (completly – soft and hard palate and uvula) staphyloschisis (uvula bifida) Figure_03-39 sekpatro_rozštepy the_end__by_m0thyyku Trávící systém I - 39 Nasal placodes Nasal pits Nasal canals Proc. frontalis Proc. nasalis medialis et lateralis Scanning+electron+micrograph+of+a+stage+15+%25288 Scanning+electron+micrograph+of+a+stage+17+%252811 Scanning+electron+micrograph+of+the+face+of+a+stage+18+%252817 stage 15 (8.0-mm), ×52. stage 17 (11.7-mm), 57x stage 17 (11.7-mm), 14x Scanning electron micrograph (SEM): human embryo Trávící systém II - 38 fetus-human-6week Trávící systém II - 39 fetus-human-6week Trávící systém II - 46 loadBinaryCA9E6INN Trávící systém III - 23 Trávící systém III - 24 Trávící systém III - 25 Trávící systém III - 26 Trávící systém III - 27 Trávící systém III - 28 Trávící systém III - 29 Trávící systém III - 30 Trávící systém III - 31 Trávící systém III - 32 Trávící systém III - 33 Trávící systém III - 35 Trávící systém III - 38 Trávící systém III - 39 Trávící systém III - 40 Gray987 PigD5L HumE6L Trávící systém I - 37 Trávící systém I - 38 Trávící systém II - 35 Trávící systém III - 36 Trávící systém III - 37 Image:Gray1101.png Trávící systém II - 42 L13I8 Trávící systém I - 34 Vývoj zubů Trávící systém I - 35 Vývoj zubů Trávící systém I - 36 Vývoj zubů dovolena6 dovolena7 dovolena8 dovolena9 Mouse-pancreas duct formation.jpg Pancreas – ducts and parenchyma development (from endoderm) Development of the duodenum and mesenteries - 5 weeks embryo, Developmental Biology PowerPoint Images, Diagrams, Templates, Slides, Illustrations http://www.vesalius.com/graphics/cf_storyboards/branchial_cyst/embG5103.jpg http://www.vesalius.com/graphics/cf_storyboards/branchial_cyst/embG5104.jpg parL5001 Ectodermal pharyngeal clefts (grooves) primitive pharynx Endodermal pharyngeal pouches Thyroid gl. Laryngotracheal diverticle fig10 fig11 Pharyngeal arches, pouches and clefts Trávící systém III - 34 At 6 weeks, the pancreatic buds meet and fuse. partitioning_tract