Talk:2010 Lab 5

Stage 13 GIT 3D Model

The individual serial slices have also been incorporated into a 3D model of this embryo [../Movies/GIT3dmodel.htm Gastrointestinal Tract].

Stage 13/14 Embryo

[../wwwpig/pigb/B1L.htm B1,B2]: Pharynx. Crest in ventral floor of pharynx formed by fusion of 3rd pharyngeal arches = hypopharyngeal eminence (precursor of root of tongue). Rathke's pouch = rudimentary adenohypophysis.

[../wwwpig/pigb/B3L.htm B3]: Rudimentary thyroid ventral to aortic sac (also seen in B2, ventral to the hypopharyngeal eminence).

[../wwwpig/pigb/B4L.htm B4]: Caudal pharynx compressed dorsoventrally.

[../wwwpig/pigb/B7L.htm B7]: Glottis drawn off from pharyngeal foregut. Nasal placodes. Pulmonary arteries.

[../wwwpig/pigc/C1L.htm C1,C2]: Commencement of trachea and oesophagus with dense mesenchyme. R. nasal pit.

[../wwwpig/pigc/C3L.htm C3,C4]: 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. L. nasal pit. In C4, junction of R common cardinal vein with dorsal wall of sinus venosus.

[../wwwpig/pigc/C5L.htm C5]: 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.

[../wwwpig/pigc/C5L.htm C5,C6]: 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.

[../wwwpig/pigc/C7L.htm C7]: Note dorsal extent of coelomic canals. Oesophagus lumen reappears caudal to bifurcation. Distinct R (smaller on L) pleuroperitoneal fold below the common cardinal vein.

[../wwwpig/pigd/D1L.htm Dl]: Oesophagus/stomach junction. Coelomic canals.

[../wwwpig/pigd/D2L.htm D2]: 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.

[../wwwpig/pigd/D3L.htm D3]: Rotation of stomach (seen from above) to R side. Note change in outline of coelomic canals due to presence of liver. Lesser sac. Note thick mesothelium lining the coelom along Ledge 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).

[../wwwpig/pigg/G7L.htm G7]: Caudal pharynx (extending laterally, ventral to dorsal aorta - cf B4). Stomach, mesentery.

[../wwwpig/pigg/G6L.htm G6]: Narrow oesophagus. Tracheal bifurcation dorsal to sinus venosus.

Stage 22 Embryo

Clicking on the section number will open the full image.

[../wwwhuman/lowpower/HumE/E6L.htm E6]: Liver. Ductus venosus. Cardio-oesophageal junction (cf. E5). Inferior vena cava.

[../wwwhuman/lowpower/HumE/E7L.htm 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.

[../wwwhuman/lowpower/HumF/F1L.htm Fl]:Stomach body. Spleen. Pyloric canal. Duodenum. Portal vein. Pancreas. Small intestine loop (jejunum) cut tangentially, ventral to liver.

[../wwwhuman/lowpower/HumF/F2L.htm 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).

[../wwwhuman/lowpower/HumF/F4L.htm 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.

[../wwwhuman/lowpower/HumF/F5L.htm F5]: Lesser sac. Greater omentum. Duodenum. Jejunum (cut twice with mesentery in between). Colon and mesocolon.

[../wwwhuman/lowpower/HumF/F6L.htm 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.

[../wwwhuman/lowpower/HumF/F7L.htm 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.

[../wwwhuman/lowpower/HumG/G1L.htm G1,G2]: Umbilical cord and coelom containing small intestine loops. Knees. Bladder with

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

[../wwwhuman/lowpower/HumG/G3L.htm G3]: Bladder. Rectum. Umbilical arteries arising from common iliac arteries.

[../wwwhuman/lowpower/HumG/G4L.htm G4]: Rectum.

[../wwwhuman/lowpower/HumG/G5L.htm G5]: Recto-anal junction with rectovesical pouch of peritoneal cavity.

[../wwwhuman/lowpower/HumG/G6L.htm G6-G7]: Anal canal with triangular lumen.