2010 Lab 5

Laboratory Notice - Mark Hill

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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
Quicktime version	Quicktime version	Quicktime version	Quicktime version	Quicktime version	Quicktime version

Gastrointestinal Tract - Mid-Embryonic (Stage 13)

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

Gastrointestinal

Stage 13 Embryo - Gastrointestinal Tract

Section	Name	Description
	B1L B2L	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 C2L	Commencement of trachea and oesophagus with dense mesenchyme. Right nasal pit.
	C3L C4L	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 C6L	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.

All Stage 13 Sections

Stage 13 (serial labeled images)

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

Gastrointestinal Tract - Late-Embryonic (Stage 22)

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

Gastrointestinal

Stage 22 Embryo - Gastrointestinal Tract

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 F3L	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 G2L	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 G7L	Anal canal with triangular lumen.

Respiratory - Mid-Embryonic (Stage 13)

Respiratory

The individual serial slices have also been incorporated into a 3D model of this embryo. The table below shows a thumbnail view of each section and a brief description of related respiratory components.

| Carnegie stage 13

Stage 13 - Respiratory

Section	Name	Description
	B1L B2L	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 C2L	Commencement of trachea and oesophagus with dense mesenchyme. Right nasal pit.
	C3L C4L	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 C6L	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.
	G7L	Caudal pharynx (extending laterally, ventral to dorsal aorta - cf B4). Stomach, mesentery
	G6L	Narrow oesophagus. Tracheal bifurcation dorsal to sinus venosus.

Respiratory - Late-Embryonic (Stage 22)

Respiratory

The individual serial slices have also been incorporated into a 3D model of this embryo. The respiratory system is endodermal in origin, initially "budding off" the foregut during week 3. This bud forms the respiratory diverticulum, at the level of the glottis between the adult oesophagus and trachea. It continues to bud in week 4, forming a pair of lung buds.

| Carnegie stage 22

Stage 22 (serial labeled images)

Section	Name	Description
	A5L	Bridge of nose. R and L olfactory bulbs from forebrain.
	A6L	Nose. Nasal septum. Nasal capsule. Olfactory epithelium lining roof of nasal cavity. Orbital part of the developing sphenoid bone (intramembranous ossification).
	A7L	Conchae. Nasal capsule and septum.
	B1L	Conchae. Optic nerve.
	B2L	Description
	B3L	Perpendicular plate of ethmoid cartilage. Adenohypophysis. Neurohypophysis. Ant. and post. walls of hypopophysial fossa. Lesser wings of sphenoid cartilage. Internal carotid arteries.
	B4L	Dorsum of tongue. Oropharynx communicating with naso-pharynx (cf. B3L - palatal processes not fused).
	B5L	Tongue with palatal processes at either side. Transverse (intrinsic) muscle of tongue. Pharyngotympanic tubes.
	B6L	Tongue with transverse muscle, genioglossus muscle (medial) and hyoglossus muscle (lateral). Palatal processes. Meckel's cartilage. Note teeth enamel organs (dark masses at sides of tongue attachment).
	B7L	Transverse caudal pharynx. epiglottis. Hyoid musculature. Pharyngeal constrictor muscle. Submandibular gland.
	C1L	Pharynx. Pharyngeal constrictor muscle. laryngeal caecum (ventral). Arytenoid swellings in contact. Thyroid cartilage laminae (anterolateral), with superior horns (posterolateral). Hyoid cartilage. Internal jugular veins. "Muz's cheshire cat"
	C2L	Pharynx. Thyroid cartilage. Smaller laryngeal caecum (cf.C1). Carotid neurovascular bundle.
	C3L	Pharynx with its inferior constrictor muscle. Glottis region.
	C4L	Oesophagus with muscle layer and trachea with thyroid gland laterally. Common carotid arteries. Vagus nerve. Internal jugular veins. (Section damaged)
	C5L	Oesophagus, smaller than in C4. Trachea. Thyroid gland (isthmus). Clavicle. Small dark masses near posterolateral borders of thyroid gland are the parathyroid glands from the caudal part of 3rd pharyngeal pouch.
	C6L	Trachea. Clavicles. Dark connecting stalk between parathyroid gland and thymus (rostral end of 3rd pharyngeal pouch). Common carotid artery.
	C7L	Trachea. Oesphagus. Apex of R lung in pleural cavity Sternum. Thymus gland. L brachiocephalic vein. Brachiocephalic trunk.
	D1L	Lungs. Visceral and parietal pleurae. Pleural cavities. Sternum. Thymus. Other contents of superior mediastinum.
	D2L	Lungs.
	D3L	Tracheal bifurcation.
	D4L	Right primary bronchus (torn) and right superior lobe bronchus. Left primary bronchus. Left and right pulmonary arteries. Ribs joining to sternum.
	D5L	R, L primary bronchi. R anterior and posterior segmental bronchi coming off R superior lobe bronchus. L, R pulmonary arteries. Hilar attachments of lungs to mediastinal tissues - note extent of R, L pleural cavities.
	D6L	R, L primary bronchi (note left still has not branched). R pulmonary artery.
	D7L	R, L primary bronchi: note distinct horizontal course of L, vertical course of R, L pulmonary veins (L empty). R pulmonary artery.
	E1L	Pulmonary veins. Azygos, hemiazygos veins. Ribs. Intercostal muscles.
	E2L	Pulmonary veins. Azygos, hemiazygos veins. Ribs. Intercostal muscles.
	E3L	R dome of diaphragm. R long middle and inferior lobes. L long superior and inferior lobes. Xiphoid process. Liver.
	E4L	Diaphragm (note costal attachment). R lung inferior lobe. Inferior vena cava, dorsal to diaphragm.
	E5L	Inferior lobes of lungs. Diaphragm with sternal attachments. Inferior vena cava, now ventral to diaphragm (vena caval foramen). Liver.
	E6L	Liver. Thoracic aorta. Large adrenal glands.
	E7L	Lumbar diaphragm. Thoracic aorta. Note ribs 11 and 12 on L and three layers of abdominal muscles extending ventrally.
	F1L	Lumbar diaphragm. Thoracic aorta.
	F2L	Attachment of lumbar diaphragm near L 1 on R with psoas muscle dorsal to it. Note abdominal aorta giving rise to superior mesenteric artery.