Development of Thyroid Gland

1. Development of Thyroid Gland
• It is developed from endodermal cells of floor of
pharynx (area of developing tongue).
• It begins a diverticulum at dorsum of tongue
between tuberculum impar and hypobranchial
eminence.
• Elongation of thyroid diverticulum to form thyro-
glossal duct. It elongates downwards infront hyoid
and thyroid cartilage where it ends by dividing into
2 parts.
• Ultimobranchial body gives parafollicular cells to
thyroid gland. Dr. Sherif Fahmy

2. Dr. Sherif Fahmy
Foramen
cecum
Thyroglossal
diverticulum
Developing anterior
2/3 of tongue

3. Dr. Sherif
Fahmy
Thyroglossal
duct
Thyroid
gland
Developing
anterior 2/3 of
tongue

4. Dr. Sherif
Fahmy
Foramen
cecum
Degenerating
thyro-glossal
duct
Hyoid bone
Thyroid
cartilage
Levator glandulae
thyroidae
Pyramidal lobe
Lobe of
thyroid gland

5. Fate of Thyro-glossal Duct
• Upper end of the duct remains as foramen cecum
on dorsum of tongue.
• The duct degenerates from foramen cecum and
hyoid bone.
• The duct from the hyoid to divisions of the duct
form levator glandulae thyroidae and may be
pyramidal lobe.
• Divisions of the duct form lobes of thyroid gland
with isthmus inbetween.
• Ultimobranchial body forms parafollicular cells of
the gland.

6. Congenital Anomalies
• Thyroid agenesis: Failure of its formation.
• Lingual thyroid: Failure of thyroid descend.
• Aberrant thyroid (Retrosternal goiter): over-
descend of thyroid gland in the thorax.
• Thyroglossal cyst: It is persistence of a part of
the thyroglossal duct.
• Thyroglossal fistula: Thyroglossal duct opens
to skin.
Dr. Sherif Fahmy

7. Dr. Sherif
Fahmy

8. Dr. Sherif
Fahmy