9: Thyroid Gland Development

Question 1

When does the thyroid start to develop?

Answer 1

24 days post fertilization (first endocrine gland to develop)

Question 2

Thyroid primordium

Answer 2

Is hollow, but becomes a solid mass

Question 3

Where does the thyroid primordium form? Where does it go?

Answer 3

Floor of primordial pharynx -> descends in neck as the tongue grows

Question 4

Thyroglossal duct

Answer 4

Tube that connects thyroid to tongue

Question 5

When does the thyroid have a definite shape? What else occurs then?

Answer 5

7 weeks; thyroglossal duct degenerates

Question 6

Ectopic thyroid tissue: location

Answer 6

Forms along thyroglossal duct; can be accessory, lingual, or cervical

Question 7

Function of ectopic thyroid tissue

Answer 7

Is still functional

Question 8

Sublingual thyroid gland

Answer 8

When thyroid forms but does not descend in the neck

Question 9

Thyroglossal duct cyst

Answer 9

Cyst forms in tongue or anterior neck - looks like an ectopic thyroid so it’s critical to distinguish before removal

Question 10

Thyroid hemiangenesis

Answer 10

Unilateral failure of thyroid formation (left more commonly absent)

Question 11

DiGeorge Syndrome

Answer 11

Agenesis of thymus and parathyroid -> congenital hypoparathyroidism

Question 12

S/S of DiGeorge Syndrome

Answer 12

Short upper lip philtrum, low-set and notched ears, nasal clefts, thyroid hypoplasia, cardiac abnormalities