Development of the gastrointestinal system Cranio-caudal folding of the embryo and formation of the primitive gut Foregut - stomodeum - membrana oropharyngea Midgut - ductus vitellinus Hindgut - proctodeum - membrana cloacae Entodermal-derived structures Processes and pharyngeal arches Aortic arches and pharyngeal pouches Developing peripherial nerves 1 Development of the face and teeth Processes: - fronto-nasal process - maxillar process - mandibular process - medial nasal process - lateral nasal process Formation of the upper lip and nasal pits Epithelial thickenings: - lens placod - nasal placod - otic placod Sulcus nasolacrimalis ductus nasolacrimalis Junction of palatine processes and nasal septum oronasal membrane, Nasal placod sinks into the deep secondary palate as the primery palate primer nasal and oral cavities lamina labiogingivalis lip, gum lamina dentalis dental bud enamel organ, dental papilla, dental sac (ectomesenchymal origin) outer and inner enamel epithelium (between them: reticulum stellatum) odontoblasts (produce predentin dentin) ameloblasts (produce enamel) cementoblasts (produce cementum) 2 Pharyngeal arches and their derivates Cleft Arch Cartilage Bone Pouch derivates Nerve derivates maxilla, mandible, ▪ auditory tube ▪ external N. trigeminus Meckel’s zygomatic bone, I. ▪ middle ear cavity auditory meatus (V.) temporal bone, malleus, incus stapes, stylod process ▪ fossa tonsillaris, N. facialis Reichert’s of os temporale, - II. palatine tonsil (VII.) rostral part of hyoid bone ▪ external parathyroid N. glosso- caudal part of - gland, - pharyngeus III. hyoid bone ▪ thymus (IX.) epiglottic ▪ internal parathyroid arytenoid N. vagus - gland, - IV-VI. thyroid (X.) ▪ ultimobranchial body cricoid inner: pharyngeal pouch - outer: pharyngeal cleft Developing organs from pharyngeal pouches and clefts Formation of the tongue: - paired lateral lingual swellings (tuberculum laterale), I. pharnygeal arch - unpaired middle swelling (tuberculum impar), I. pharnygeal arch - copula (gradually atrophies) II. pharnygeal arch - eminentia hypobranchialis III-IV. pharnygeal arch Tongue muscles from occipital myotom their nerve is the n. hypoglossus (XII.) Ductus thyreoglossus gl. thyreoidea (thyroid gland) 3 Development of the gut I. Main vessels supplying the gut Curvatura major and minor Formation of the intraembrional coelom, mesenterium dorsale and ventrale Mesogastrium dorsale and ventrale Recessus pneumo-entericus bursa omentalis + bursa infracardiaca Dorsal and ventrali pancreatic buds, developing liver Rotation around the cranio-caudal axis Rotation around the dorso-ventral axis (~90° turn, to the left) (~45° turn: cardia gets to the left, pylorus to the right) Development of the ruminant composite stomach 4 Development of the gut II. left side view left side view right caudo-dorsal view 5 Separation of the hindgut cloaca septum urorectale separates membrana analis and rectum and sinus urogenitalis membrana urogenitalis Some congenital anomalies cleft palate, cleft lip umbilical hernia Meckel’s diverticulum cyst fibrous chord fistula stenosis obstruction 6 .