Gastrointestinal Tract - Carnegie Stage 13

From Embryology




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

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GIT Histology Links: Upper GIT | Salivary Gland | Smooth Muscle Histology | Liver | Gallbladder | Pancreas | Colon | Histology Stains | Histology | GIT Development
Historic Embryology - Gastrointestinal Tract  
1878 Alimentary Canal | 1882 The Organs of the Inner Germ-Layer The Alimentary Tube with its Appended Organs | 1884 Great omentum and transverse mesocolon | 1902 Meckel's diverticulum | 1902 The Organs of Digestion | 1903 Submaxillary Gland | 1906 Liver | 1907 Development of the Digestive System | 1907 Atlas | 1907 23 Somite Embryo | 1908 Liver | 1908 Liver and Vascular | 1910 Mucous membrane Oesophagus to Small Intestine | 1910 Large intestine and Vermiform process | 1911-13 Intestine and Peritoneum - Part 1 | Part 2 | Part 3 | Part 5 | Part 6 | 1912 Digestive Tract | 1912 Stomach | 1914 Digestive Tract | 1914 Intestines | 1914 Rectum | 1915 Pharynx | 1915 Intestinal Rotation | 1917 Entodermal Canal | 1918 Anatomy | 1921 Alimentary Tube | 1932 Gall Bladder | 1939 Alimentary Canal Looping | 1940 Duodenum anomalies | 2008 Liver | 2016 GIT Notes | Historic Disclaimer
Human Embryo: 1908 13-14 Somite Embryo | 1921 Liver Suspensory Ligament | 1926 22 Somite Embryo | 1907 23 Somite Embryo | 1937 25 Somite Embryo | 1914 27 Somite Embryo | 1914 Week 7 Embryo
Animal Development: 1913 Chicken | 1951 Frog

| Carnegie stage 13

Stage 13 - Gastrointestinal Tract
Section Name Description
Stage 13 image 057.jpg

Stage 13 image 058.jpg




Head arches cartoon.jpg Note how in this region it is arched over and cut twice in this section.

The righthand side towards the buccopharyngeal membrane, the lefthand side descending into the embryo body. Stage13 B2 excerpt.gif

Central region is the floor of pharynx formed by fusion of 3rd pharyngeal arches = hypopharyngeal eminence (precursor of root of tongue).

Rathke's pouch forming the rudimentary adenohypophysis (anterior pituitary).

Stage 13 image 059.jpg B3L Laryngeal tracheal groove - beginning of ventral compression, at 90 degrees to the lateral plane of the pharynx above this point.

Rudimentary thyroid ventral to aortic sac (also seen in B2, ventral to the hypopharyngeal eminence).

Stage 13 image 060.jpg B4L Laryngeal tracheal groove - Caudal pharynx compressed dorsoventrally.

Note that it lies between the aortic sac (ventrally) directly above the heart and the paired vessels of arch artery 6 and the dorsal aortas. The pale staining region behind these blood vessels is where the vertebral column will form.

Stage 13 image 061.jpg B5L Laryngopharynx - now compressed dorsoventrally between the paired arch artery 6 vessels.
Stage 13 image 063.jpg B7L Glottis - initial separation of the oesophagus (dorsal) from the trachea (ventral).

Note that this is occurring at the level of the heart atria.

Nasal placodes. Pulmonary arteries.

Stage 13 image 064.jpg C1L Gastrointestinal tract oesophagus (dorsal) is now separate from the respiratory trachea (ventral).
Stage 13 image 065.jpg C2L Oesophagus and trachea both surrounded by dense mesenchyme.

Right nasal pit.

Stage 13 image 066.jpg

Stage 13 image 067.jpg



Oesophagus and trachea both surrounded by dense mesenchyme.

Common cardinal vein in the posterior wall of the intraembryonic coelom.

The pleuropericardial folds which contribute later to the formation of the pleura and pericardium.

In C4, junction of right common cardinal vein with dorsal wall of sinus venosus.

Left nasal pit.

Stage 13 image 068.jpg C5L Smaller oesophagus and expanding trachea, this is also the upper region of the lung buds.

The ventral anchoring of attachment site is at the most cranial extension of the septum transversum. This attachment now divides the intraembryonic coelom around the trachea into two canals, the left and right pleuro (pericardio-peritoneal) canals.

Canals are lined by coelomic mesothelium and are continuous with whole intraembryonic coelom (they will be referred to hereafter simply as coelomic canals).

The pleuroperitoneal fold on the medial side of the right common cardinal vein will form part of the diaphragm.

Stage 13 image 069.jpg C6L Trachea expanded and beginning to bifurcate to the major bronchial branches for each lung.

Lateral extension of pulmonary mesenchyme is moulded to shape of coelomic canals. Oesophagus lumen obliterated (common site of oesophageal atresia and/or tracheo-oesophageal fistula). Prominent R pleuroperitoneal fold.

Stage 13 image 070.jpg C7L Trachea bifurcated to the major bronchial branches for each lung.

Note dorsal extent of coelomic canals.

Oesophagus lumen reappears caudal to bifurcation.

Distinct R (smaller on L) pleuroperitoneal fold below the common cardinal vein.

Stage 13 image 071.jpg D1L Oesophagus/stomach junction.

Right lung bud bronchus still visible, left bronchus ends above this section. Note the oesophagus now lies in the midline between the 2 bronchi.

Coelomic canals.

Stage 13 image 072.jpg D2L Ovoid stomach with developing space of the lesser sac on R.

Dorsal and ventral attachments of the mesenchyme are now known as dorsal and ventral mesogastria. Coelomic canals.

Stage 13 image 073.jpg D3L Rotation of stomach (seen from above) to right side.

Note change in outline of coelomic canals due to presence of liver.

Lesser sac. Note thick mesothelium lining the coelom along left edge of stomach, the primordium of the spleen and greater omentum along greater curvature.

Liver embedded in septum transversum (ventral border of septum transversum contributes to diaphragm).

Stage 13 image 074.jpg D4L Rotation of stomach (seen from above) to right side.

Ventral mesogastrium - Stomach is attached ventrally to the liver. (note the position of the ductus venosus)

Dorsal mesogastrium - within this structure the spleen will begin to form and later the greater omentum.

Peritoneal spaces - identify greater and lesser sac.

Stage 13 image 076.jpg D6L Pyloric region of stomach.

Ventral mesogastrium - Stomach is closely attached ventrally to the liver.

Dorsal mesogastrium - within this structure the spleen will begin to form and later the greater omentum.

Peritoneal spaces - identify greater and lesser sac.

Stage 13 image 081.jpg E4L Midgut.

Region close to the umbilicus. Note the close associated portal vein and the paired placental (umbilical) veins.

Stage 13 image 085.jpg F1L Midgut.

Looping out of body wall ventrally (cut tangentially).

Also note the righthand side hindgut region.

Stage 13 image 098.jpg G7L Caudal pharynx (extending laterally, ventral to dorsal aorta - cf B4). Stomach, mesentery
Stage 13 image 097.jpg G6L Narrow oesophagus. Tracheal bifurcation dorsal to sinus venosus.

All Sections

Stage 13 (serial labeled images)
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Cite this page: Hill, M.A. (2024, June 22) Embryology Gastrointestinal Tract - Carnegie Stage 13. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G