Endo - Embryology

Question 1

From where does the Thyroid diverticulum arise? How does it reach its adult position from there?

Answer 1

Thyroid diverticulum arises from floor of primitive pharynx, descends into neck

Question 2

What connects the thyroid to the tongue? What is normal fate of this structure? What is an alternative fate? What is the normal remnant of this structure called?

Answer 2

Thyroglossal duct; Normally disappears, but may persist as pyramidal lobe of thyroid; Foramen cecum

Question 3

What is the most common ectopic thyroid tissue site?

Answer 3

The tongue

Question 4

What is the role played by thyroglossal duct in development?

Answer 4

Connects thyroid to tongue

Question 5

What is the foramen cecum?

Answer 5

Normal remnant of thyroglossal duct

Question 6

How does a Thyroglossal duct cyst present? What can this presentation be contrasted against?

Answer 6

Presents as an anterior midline neck mass that moves with swallowing or protrusion of the tongue (vs. persistent cervical sinus leading to branchial cleft cyst in lateral neck)

Question 7

Draw the structure of Thyroid. Include labels for the following structures: (1) Thyroid gland (2) Thymus (3) Trachea (4) Persistent thyroglossal duct (5) Foramen cecum.

Answer 7

See First Aid 2014 p. 306 or 2013 p. 286 (image at top on right)

Question 8

Of what zones does the fetal adrenal gland consist?

Answer 8

(1) Outer adult zone (2) Inner active fetal zone

Question 9

What role(s) does the adult zone of the fetal adrenal gland play, and at what general stages of gestation?

Answer 9

Adult zone is dormant during early fetal but begins to secrete cortisol late in gestation

Question 10

What controls cortisol secretion in the fetus, and from what does/do it/they orginate?

Answer 10

Cortisol secretion is controlled by ACTH and CRH from fetal pituitary and placenta

Question 11

For what 2 physiologic consequences in the fetus is cortisol responsible?

Answer 11

(1) Fetal lung maturation (2) Surfactant production