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24 Cards in this Set
- Front
- Back
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What are the 3 fates of pharyngeal endoderm?
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1. Salivary glands
2. Thyroid gland 3. Pharyngeal pouches |
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What tissue type are the salivary glands derived from?
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Ectoderm - from epithelial ectoderm that invaginates into adjacent mesenchyme.
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What is the difference between exocrine and endocrine glands?
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Exocrine retain a connection with surface epithelium
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What 2 types of abnormalities occur with salivary gland devo?
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-Agenesis (rare) - decreased saliva production
-Ranula - enlarged gland due to a nonpatent duct |
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Where does Thyroid Gland formation begin?
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As a diverticulum between the lingual swellings -> Foramen cecum in adult
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What arches contribute the Thyroid?
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1 and 2
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What is the thyroglossal Duct?
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What we call the thyroid after the initial diverticulum disconnects from the pharynx and becomes hollow (patent)
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In what direction does the thyroglossal duct displace?
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Caudally - to the neck from the pharynx.
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What happens to the thyroglossal ductal connection from the pharynx to the neck after migration of the bilobed thyroid?
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It disappears.
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What does agenesis of the thyroid lead to?
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Cretinism
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What is cretinism?
3 symptoms: |
Form of dwarfism
-Mental retardation -Growth retardation -Dry skin |
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What 2 conditions can develop from a Persistent Thyroglossal Duct?
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-Cysts
-Fistulas |
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What is the main difference between a cyst and fistula?
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Cysts - not usually open
Fistula - sinuses which are the result of a ruptured cyst. |
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What is a Persistent Thyroglossal Duct Cyst?
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A midline cyst occurring anywhere between the tongue and normal thyroid position.
-any age -not normally open to skin |
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What is the common name for an aberrant thyroid tissue in the tongue?
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Lingual thyroid
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Where is a lingual thyroid usually located?
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Within the body of the tongue at the foramen cecum.
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Fate of 1st Pharyngeal Pouch:
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-Retains connection to pharynx
-Becomes auditory tube, middle ear cavity |
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Fate of 2nd Pharyngeal Pouch:
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Palatine tonsil
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Fate of 3rd Pharyngeal Pouch:
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Two Wings:
-Dorsal = inferior parathyroids -Ventral = Thymus |
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Fate of 4th Pharyngeal Pouch:
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Superior parathyroids
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Fate of 5th Pharyngeal Pouch:
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Ultimobranchial body; gets infiltrated by neural crest cells; Becomes C Cells of thyroid.
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What is the main thyroid devo defect to remember?
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Di George syndrome
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What are the symptoms of Di George Syndrome?
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Low ears, hypoplastic mandible
Thymic aplasia, hypoparathyroids Heart defects, cleft palate |
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What is thought to be the cause of Di George syndrome?
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Insufficient neural crest cell migration.
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