Development of the gastrointestinal system

Cranio-caudal folding of the embryo and formation of the primitive gut

Foregut - - membrana oropharyngea - ductus vitellinus

Hindgut - - membrana cloacae Entodermal-derived structures

Processes and pharyngeal arches Aortic arches and pharyngeal pouches Developing peripherial nerves

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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 Junction of palatine processes and nasal septum  ductus nasolacrimalis

oronasal membrane, Nasal placod sinks into the deep  secondary primer nasal and oral cavities as the primery palate

 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)

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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 : - 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

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Development of the gut II. left side view

left side view

right caudo-dorsal view

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Separation of the

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

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