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.
The materials used in this class can also be seen at the following links: Gastrointestinal Tract - Carnegie Stage 13 | Stage 22 | Respiratory System - Carnegie Stage 13 | Respiratory System - Carnegie Stage 22
Gastrointestinal Tract Movies
Gastrointestinal Tract - Mid-Embryonic (Stage 13)
The individual serial slices have also been incorporated into a 3D model of this 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. |
Gastrointestinal Tract - Late-Embryonic (Stage 22)
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
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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. |
Respiratory - Mid-Embryonic (Stage 13)
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. | |
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)
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. |
Respiratory Links: respiratory | Science Lecture | Lecture Movie | Med Lecture | Stage 13 | Stage 22 | upper respiratory tract | diaphragm | Histology | Postnatal | respiratory abnormalities | Respiratory Quiz | Respiratory terms | Category:Respiratory | ||
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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. |
Early Fetal (Week 10)
The fetal period is a time of extensive growth in size and mass as well as differentiation of organ systems established in the embryonic period. In particular, the brain continues to grow and develop, the respiratory system differentiates, the urogenital system further differentiates between male/female, endocrine and gastrointestinal tract begins to function.
These 4 images are from a 10 week female fetus approximately 40 mm in size. This stage of development is after the embryonic period (up to week 8), but only 2 weeks into early fetal development.
Compare this 10 week fetus with the earlier Carnegie stage embryos in relation to gastrointestinal tract and respiratory development.
Note:
- The structure, size and position of the early fetal lungs.
- The relatively underdeveloped diaphragm.
- The position of the stomach and liver.
- The midgut herniated at the umbilicus and will only be taken into the peritoneal cavity on further body wall growth.
- The herniated midgut remains attached to the posterior body wall by its mesentery.
- The hindgut rectum is now separated from the ventral urogenital region.
Fetal Links: fetal | Week 10 | Week 12 | second trimester | third trimester | fetal neural | Fetal Blood Sampling | fetal growth restriction | birth | birth weight | preterm birth | Developmental Origins of Health and Disease | macrosomia | BGD Practical | Medicine Lecture | Science Lecture | Lecture Movie | Category:Human Fetus | Category:Fetal | |||
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There are 4 sections taken in the sagittal plane (moving from the right at Plane A towards the midline at Plane D). Click on the small images (or the text below) to open the linked large image pages.
Related Images
Fetus (week 10) Planes A (most lateral), B (lateral), C (medial) and D (midline) from lateral towards the midline.
- Human Fetus - most lateral | lateral | medial | midline
- Head - most lateral | lateral | medial | midline
- Cerebellum - most lateral | lateral | medial | midline
- Urogenital Unlabelled - most lateral | lateral | medial | midline
- Urogenital Labelled - most lateral | lateral | medial | midline
- Large Images - midline
- Image Source: UNSW Embryology, no reproduction without permission.