2010 Lab 5
Introduction
This laboratory will allow time to study both gastrointestinal tract and respiratory development. The class will study features and events of development occurring: early-embryonic, mid-embryonic, late-embryonic and fetal.
Gastrointestinal Tract Movies
Endoderm | Yolk Sac | Tract Growth | Stomach Rotation | Lesser Sac | Greater Omentum |
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Stage 13 GIT 3D Model
The individual serial slices have also been incorporated into a 3D model of this embryo.
Stage 13/14 Embryo
Section | Name | Description |
---|---|---|
B1L | Pharynx.
Crest in ventral 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). | |
B3L | Rudimentary thyroid ventral to aortic sac (also seen in B2, ventral to the hypopharyngeal eminence). | |
B4L | Caudal pharynx compressed dorsoventrally. | |
B7L | Glottis drawn off from pharyngeal foregut.
Nasal placodes. Pulmonary arteries. | |
C1L | Commencement of trachea and oesophagus with dense mesenchyme.
Right nasal pit. | |
C3L | 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. | |
C5L | Smaller oesophagus, expanding trachea. Note ventral anchoring of attachment site is at the most cranial extension of the septum transversum.
Note also that this attachment now divides the intraembryonic coelom around the trachea into two canals, the L and R pleuro (pericardio-peritoneal) canals. (Canals are lined by coelomic mesothelium and are continuous with whole I-E coelom - they will be referred to hereafter simply as coelomic canals). Note the pleuroperitoneal fold on the medial side of the R common cardinal vein - this fold will form part of the diaphragm. | |
C5L | 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. | |
C7L | Note dorsal extent of coelomic canals.
Oesophagus lumen reappears caudal to bifurcation. Distinct R (smaller on L) pleuroperitoneal fold below the common cardinal vein. | |
D1L | Oesophagus/stomach junction. Coelomic canals. | |
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. | |
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). | |
G7L | Caudal pharynx (extending laterally, ventral to dorsal aorta - cf B4). Stomach, mesentery | |
G6L | Narrow oesophagus. Tracheal bifurcation dorsal to sinus venosus. |
Test
A1L | A2L | A3L | A4L | A5L | A6L | A7L |
B1L | B2L | B3L | B4L | B5L | B6L | B7L |
C1L | C2L | C3L | C4L | C5L | C6L | C7L |
D1L | D2L | D3L | D4L | D5L | D6L | D7L |
E1L | E2L | E3L | E4L | E5L | E6L | E7L |
F1L | F2L | F3L | F4L | F5L | F6L | F7L |
G1L | G2L | G3L | G4L | G5L | G6L | G7L |
Stage 22 Embryo
The individual serial slices have also been incorporated into a 3D model of this embryo.
Section | Name | Description |
---|---|---|
E6L | Liver. Ductus venosus.
Cardio-oesophageal junction (cf. E5). Inferior vena cava. | |
E7L | 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. | |
F1L | Stomach body. Spleen. Pyloric canal. Duodenum.
Pancreas. Small intestine loop (jejunum) cut tangentially, ventral to liver. Portal vein. | |
F2L | 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). | |
F4L | 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. | |
F5L | Lesser sac. Greater omentum. Duodenum. Jejunum (cut twice with mesentery in between). Colon and mesocolon. | |
F6L | Greater omentum and lesser sac.
Jejunum with mesentery. Colon with mesocolon. Three layers of abdominal muscles. Both umbilical arteries now inside abdominal cavity with urachus between them. | |
F7L | In abdominal cavity - colon with mesocolon, jejunum. Greater omentum and lesser sac.
Umbilical cord - containing umbilical arteries and small dark allantois. Umbilical cord coelom containing mainly, small intestinal loops with their mesentery. | |
G1L
|
Umbilical cord and coelom containing small intestine loops.
Colon and mesocolon. Jejunum (G1 only). Bladder with umbilical arteries either side. Knees. | |
G3L | Rectum.
Bladder. Umbilical arteries arising from common iliac arteries. | |
G4L | Rectum. | |
G5L | Recto-anal junction with rectovesical pouch of peritoneal cavity. | |
G6L | Anal canal with triangular lumen. |
A1L | A2L | A3L | A4L | A5L | A6L | A7L |
B1L | B2L | B3L | B4L | B5L | B6L | B7L |
C1L | C2L | C3L | C4L | C5L | C6L | C7L |
D1L | D2L | D3L | D4L | D5L | D6L | D7L |
E1L | E2L | E3L | E4L | E5L | E6L | E7L |
F1L | F2L | F3L | F4L | F5L | F6L | F7L |
G1L | G2L | G3L | G4L | G5L | G6L | G7L |