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UNSW Embryology

Gastrointestinal Tract Stage 22 Embryo

© Dr Mark Hill (2008)

Acknowledgements

Introduction

Stage 22 GIT 3D Model

The individual serial slices have also been incorporated into a 3D model of this embryo Gastrointestinal Tract.

Stage 22 Embryo

Clicking on the section number will open the full image.

E6: Liver. Ductus venosus. Cardio-oesophageal junction (cf. E5). Inferior vena cava.

E7: Stomach body, with mucosa, submucosa and muscularis externa. Lesser sac. Lesser omentum. Pyloroduodenal junction. Folded duodenal mucosa. Inferior vena cava. Portal vein. Hepatic ducts. Gallbladder.

Fl:Stomach body. Spleen. Pyloric canal. Duodenum. Portal vein. Pancreas. Small intestine loop (jejunum) cut tangentially, ventral to liver.

F2,F3: Stomach, spleen. Superior mesenteric artery. Superior mesenteric vein crossing cranial to body of pancreas. Tail of pancreas. Duodenum. Small intestinal loop herniating from abdominal cavity into the coelom of the umbilical cord (remnant of extra-embryonic coelom).

F4: Greater curvature of stomach (tangential section). Lesser sac. Greater omentum. Duodenal/jejunal junction. Note colon (small lumen, darkly-staining wall) and its mesocolon. Note the sections of small and large intestine within the umbilical cord coelom and their mesenteries. Note the thickened jelly to one side of the umbilical cord, containing umbilical vein and R umbilical artery.

F5: Lesser sac. Greater omentum. Duodenum. Jejunum (cut twice with mesentery in between). Colon and mesocolon.

F6: Both umbilical arteries now inside abdominal cavity with urachus between them. Greater omentum and lesser sac. Jejunum with mesentery. Colon with mesocolon. Three layers of abdominal muscles.

F7: Umbilical cord containing umbilical arteries and small dark allantois. Umbilical cord

coelom containing mainly, small intestinal loops with their mesentery. In abdominal cavity:

colon with mesocolon, jejunum. Greater omentum and lesser sac.

G1,G2: Umbilical cord and coelom containing small intestine loops. Knees. Bladder with

umbilical arteries either side. Colon and mesocolon. Jejunum (G1 only).

G3: Bladder. Rectum. Umbilical arteries arising from common iliac arteries.

G4: Rectum.

G5: Recto-anal junction with rectovesical pouch of peritoneal cavity.

G6-G7: Anal canal with triangular lumen.

Stage 22 Embryo (Human)

A1

A2

A3

A4

A5

A6

A7

B1

B2

B3

B4

B5

B6

B7

C1

C2

C3

C4

C5

C6

C7

D1

D2

D3

D4

D5

D6

D7

E1

E2

E3

E4

E5

E6

E7

F1

F2

F3

F4

F5

F6

F7

G1

G2

G3

G4

G5

G6

G7

Glossary of Terms

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