Emrbyology Flashcards
1
Q
what does the thyroid develop from?
A
evagination of the pharyngeal epithelium at the 4th week of embryogenesis
2
Q
how does the thyroid develop?
A
descends from the foramen caecum in the middle of the tongue in front of the larynx to its normal location along the thyroglossal duct
3
Q
what does the thyroid come into close contact with?
A
lowest part of the pharynx which will become future C cells
4
Q
abnormalities in thyroid development
A
- failure of descent= lingual thyroid
- excessive descent= retrosternal thyroid (mediastinum)
- thyroglossal duct cysts can develop at any part of the migratory pathway
- pyramidal lobe if the thyroglossal duct does not lose contact
5
Q
how has the thyroid development at the end of month 2 of embryogenesis
A
2 lobes are joined at the isthmus in front of the trachea
6
Q
what has developed by 12 weeks embryogenesis
A
primitive follicles surround the central lumen that can now trap iodine and respond to TSH
