1

Development of the gastrointestinal system

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

Entodermal-derived structures

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

Foregut

- stomodeum

- membrana oropharyngea

Midgut

- ductus vitellinus

Hindgut

- proctodeum

- membrana cloacae

2

Development of the face and teeth

Processes:

- fronto-nasal process

- maxillar process

- mandibular process

- medial nasal process

- lateral nasal process

Epithelial thickenings:

- lens placod

- nasal placod

- otic placod

oronasal membrane,

as the primery palate Nasal placod sinks into the deep

primer nasal and oral cavities

Sulcus nasolacrimalis

ductus nasolacrimalis Junction of palatine processes and nasal septum

secondary palate

Formation of the upper lip and nasal pits

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)

3

Pharyngeal arches and their derivates

Arch Cartilage Bone Pouch derivates Cleft

derivates Nerve

I. Meckel’s

maxilla,

mandible,

zygomatic bone, temporal bone,

malleus, incus

▪ auditory tube

▪ middle ear cavity

▪ external

auditory meatus

N. trigeminus

(V.)

II. Reichert’s

stapes, stylod process

of os temporale, rostral part of

hyoid bone

▪ fossa tonsillaris, palatine tonsil

- N. facialis

(VII.)

III. - caudal part of

hyoid bone

▪ external parathyroid

gland,

▪ thymus

-

N. glosso-

pharyngeus

(IX.)

IV-VI.

epiglottic

arytenoid

thyroid cricoid

- ▪ internal parathyroid

gland,

▪ ultimobranchial body

- N. vagus

(X.)

Formation of the tongue:

- paired lateral lingual swellings (tuberculum laterale),

- unpaired middle swelling (tuberculum impar),

- copula (gradually atrophies)

- eminentia hypobranchialis

inner: pharyngeal pouch - outer: pharyngeal cleft

Developing organs from pharyngeal pouches and clefts

I. pharnygeal arch

I. pharnygeal arch

II. pharnygeal arch

III-IV. pharnygeal arch

Tongue muscles from occipital myotom their nerve is the n. hypoglossus (XII.)

Ductus thyreoglossus gl. thyreoidea (thyroid gland)

4

Development of the gut I.

Dorsal and ventrali pancreatic buds, developing liver

Development of the ruminant composite stomach

Formation of the intraembrional coelom,

mesenterium dorsale and ventrale

Main vessels supplying the gut

Rotation around the cranio-caudal axis

(~90° turn, to the left)

Curvatura major and minor

Rotation around the dorso-ventral axis

(~45° turn: cardia gets to the left, pylorus to the right)

Mesogastrium dorsale and ventrale

Recessus pneumo-entericus

bursa omentalis + bursa infracardiaca

5

Development of the gut II.

left side view

left side view

right caudo-dorsal view

6

Separation of the hindgut

Some congenital anomalies

umbilical hernia cleft palate, cleft lip

cloaca septum urorectale separates

rectum and sinus urogenitalis

membrana analis and

membrana urogenitalis

Meckel’s diverticulum cyst fistula

stenosis obstruction

fibrous chord