Pharyngeal Pouches

Question 1

What are the pouches /grooves

Answer 1

In between each arch on the outside is a groove /inside is a pouch

Question 2

1st pouch/groove

Answer 2

Invaginate to form the middle , inner , external ears/auditory tubes , also the pharyngotympanic tube .

Question 3

2/3/4th grooves

Answer 3

They vanish ; they become pinched off , remain connected to ectoderm by cervical sinus . Eventually become sealed off from the skin

Question 4

2nd pouch

Answer 4

Forms tonsillar bead of palatine tonsil .

Question 5

3/4th pouches

Answer 5

Give off dorsal /ventral wings
3rd = dorsal wing gives off the inferior parathyroid gland , ventral wing gives rise to the thymus .
4th = dorsal wing gives off superior parathyroid gland . Ventral wing produces C cells of thyroid .
These then migrate Off and join the thyroid gland .
On front of cervical muscles , the thyroid gland becomes Situated .
Thymus migrates inferiorly to superior mediastinum .