UNSW Embryology

Head and Neck Development - Stage 13/14

© Dr Mark Hill (2008)

Acknowledgements

Introduction

This current page gives a brief overview of early embryonic development (Carnegie stage 13/14) in the head and neck region.

Stage 13 embryo

Page Links: Introduction | Overview | Arches Overview | Otocyst | Pharynx | Sections by Text | References | Search Pubmed | Glossary | Terms

Stage 13/14 Embryo

Overview of Pharyngeal Arches

Stage 13/14 Embryo

Otocyst Overview

A2: Otocyst (R). Apex of otocyst (primordium of L endolymphatic sac).   See also Senses Notes	A3: Otocyst; surrounding mesenchyme = otic capsule. Note proximity of otocyst to wall of rhombencephalon. Superior glossopharyngeal ganglion. Vestibulo-cochlear-facial ganglion complex (R). Trigeminal ganglion (not in image excerpt).	A4: Indentation in rostral margin of otocyst = primordium of utriculosaccular canal. Note alignment of superior cardinal vein (LS) in relation to the nerve trunks (XS). Trigeminal ganglion (not in image excerpt). Note variation in height of cells of L otocyst wall. Dorsal end of 1st pharyngeal arch and groove (not in image excerpt).	A5: Facial ganglion (R). "Floor" of L otocyst. Note on R, the former position of the otocyst in relation to the 2nd pharyngeal arch.

Stage 13/14 Embryo

Pharynx Overview

A6: 1st, 2nd arches, grooves and pouches on R. Inferior glossopharyngeal and facial ganglia on left.	A7: 1st pharyngeal pouch opening into pharynx. A portion of which can be seen in the embryo midline.	B1: The pharynx is forming a tight arch sectioned twice. 1st pharyngeal pouch opening into pharynx. Hypopharyngeal eminence (=hypobranchial eminence) can be seen in middle of image.
	B2: The pharynx is forming a tight arch sectioned twice. 1st pharyngeal pouch opening into pharynx. Hypopharyngeal eminence (=hypobranchial eminence) can be seen in middle of image. Dark spots within the hypopharyngeal eminence are the "cords" of thyroid precursor cells descending from the pharynx floor to form the thyroid gland in the neck. Thyroid has an important endocrine role in later development. B3: Aortic sac with emerging 3rd arch artery. Thyroid cords. Arches l- 4. 4th arch arteries. Note at midline compression in the pharynx floor as it approaches the glottis.

B1: Rathke's pouch. Roof of pharynx can be seen on left of image. Developing diencephalon. Lens pit (arrowed, derived from lens placode).	B2: Rathke's pouch. Optic cup with optic ventricle.	B2: Note how close roof of pharynx is to the floor plate region of the neural tube (diencephalon).

Stage 13/14 Embryo - Sections by Text

A text description linked to the actual embryo cross-section.

A2,A3: Otocyst, otic capsule, rhombencephalon and rhombomeres.

A3,A4: Trigeminal ganglion, dorsal end of 1st pharyngeal arch, vestibulocochlear ganglion (rostral to otocyst), superior glossopharyngeal ganglion.

A4: Large head vein lateral to otocyst. Mesencephalon

A5: Trigeminal ganglion, facial ganglion, large head (superior (anterior) cardinal) vein lateral to inferior (cut) end of otocyst, mesencephalon (midbrain). 2nd pharyngeal arch.Vagus nerve in lateral wall of superior cardinal vein.

A6: Midbrain, floor of hindbrain with 4th ventricle, spinal cord, notochord. 1st, 2nd, 3rd pharyngeal arches with 1st and 2nd pharyngeal pouches, pharyngeal clefts. Trigeminal, facial, inferior glossopharyngeal ganglia, vagus nerve.

A7: 4th arch with inferior vagal ganglion. Arch arteries (cf. B 1, B2). Cut roof of pharyngeal cavity in midline and laterally.

B1: Division of 1st arch into mandibular and maxillary components on one side (undivided on other side due to alignment of embryo at sectioning). Dorsal portion of hypopharyngeal hypo-branchial) eminence. Prominent 3rd arch artery, dorsal aortae. Rathke's pouch (derived from ectoderm anterior to the buccopharyngeal membrane). prosencephalon. Note thin pharyngeal pouch/groove membranes

B2: Rathke's pouch. Dorsal part of pharyngeal cavity. 3rd arch artery. 4th arch artery joining to dorsal aorta. 2nd and 3rd pouches with their corresponding grooves. Optic cup and lens placode. Thyroid rudiment (cords) near midline. Note that the opening to the pharynx is located between B l and B2 - the site of the former buccopharyngeal membrane.

B3: Aortic sac with emerging 3rd arch artery. Thyroid cords. Arches l- 4. 4th arch arteries.

B4: Aortic sac with emerging 4th arch artery. Tangential section through optic stalk. Division of first arch into mandibular and maxillary processes. Pharynx. Note increasingly thick ectoderm of pharyngeal arches.

B5: Ventral ends of mandibular processes, maxillary process on one side and nasal placode on other side. Optic cup connected by optic stalk to wall of forebrain (continuous lumen). Note that pharynx has become compressed laterally (compare B4).

B6: Note the ventral compression of the pharynx into a plate and the dense mesenchyme laterally. Two atria and midline truncus arteriosus of heart. Thick nasal placode.

B7: Glottis coming off pharyngeal foregut. Nasal placode. Prosencephalon.

C1-C7: Beginning of trachea, oesophagus. Nasal placodes (nasal pit forming on one side). Forebrain. note proximity of nasal pit to prosencephalon (future site of olfactory nerve). In C2-C4, identify the medial and lateral nasal swellings.

G7: (Close to midline in head region). Forebrain, midbrain, hindbrain (with thin roof). Rathke's pouch. Floor of pharynx with foramen caecum (the tongue has not yet formed). Aortic sac. Cephalic flexure at side of midbrain between forebrain and hindbrain. Cervical flexure at junction of spinal cord and hindbrain.

G6: Mandibular process of 1st arch. Pharyngeal aspect of 1st, 2nd, 3rd arches. 3rd arch artery above truncus arteriosus. Pharynx leading into oesophagus. Ventral to oesophagus is the dense mesenchyme laterally compressing the pharynx. Notochord. Cephalic flexure and cervical flexure.

Stage 13/14 Embryo - Section Links

	A1	A2	A3	A4	A5	A6	A7
	B1	B2	B3	B4	B5	B6	B7
	C1	C2	C3	C4	C5	C6	C7
	D1	D2	D3	D4	D5	D6	D7
	E1	E2	E3	E4	E5	E6	E7
	F1	F2	F3	F4	F5	F6	F7
	G1	G2	G3	G4	G5	G6	G7

References

Reviews

Search Pubmed Now: head+development

Glossary of Terms

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Development Terms

• anlage- (Ger. ) primordium, structure or cells which will form a future structure.
• buccopharyngeal membrane- (=oral membrane) at cranial (mouth) end of gastrointestinal tract (GIT) where surface ectoderm and GIT endoderm meet.

Quick Links

Head and Neck Pages:

| References | Abnormalities | OMIM | Questions | Medline | Pig Stage 13/14 | Human (Stage22) | Human (stage 22) | Selected Human (stage 22) | Text only page | WWW Links

Development Notes ----------------- Menstrual Cycle Week 1 Week 2 Week 3 Week 4 Placenta Serial Images Genes/DNA Molecular Dev Abnormal Dev Postnatal Dev Notes Index

System Notes ----------------- Heart/Cardiovascular Respiratory Coelomic cavity Gastrointestinal Tract Head and Neck Neural Neural Crest Eye Ear Nose Endocrine Urogenital Musculoskeletal Integumentary

Movies ----------------- Embryo Growth Ultrasound Week 1 Week 2 Week 3 Week 4 Stage 13/14 Stage 22 Neural Head and Neck Heart Vasculature Gastrointestinal Urogenital Other Embryos Larsen Internet

Other Embryos ----------------- Chicken Fly Frog Mouse Rabbit Rat Worm Zebrafish Guinea Pig

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