Pouches

Question 1

Pouch 1 develops into?

Answer 1

the AUDITORY TUBE and middle ear cavity
*tubotympanic recess (primitive TYMPANIC CAVITY or middle ear cavity and pharyngotympanic tube (eustachian), inner lining of tympanum)

Question 2

Pouch 2 forms numerous infoldings that become?

*later what infiltrates it?

Answer 2

the crypts of the palatine tonsil
*later, lymphocytes (from the thymus and bone marrow) infiltrate the underlying lamina propria to establish the definitive palatine tonsil (invaded by mesoderm?)

Question 3

Pouch 3 AND pouch 4 divides into?

Answer 3

superior (dorsal) and inferior (ventral) portions

Question 4

dorsal portion of pouch 3 forms the?

*the ____ cells are are derived from the ____ lining of the pouch

Answer 4

inferior parathyroid glands

*the chief (or principle) and oxyphile cells are derived from the endodermal lining of the pouch

Question 5

ventral portion of pouch 3 forms the?

Answer 5

thymus

Question 6

what cells are derived from the endodermal lining of the ventral portion of pouch 3?

Answer 6

epithelial reticular cells (including those that comprode the thymic or Hassall’s corpuscles) are derived from the endodermal lining of the pouch

Question 7

what establishes the definitive thymus in the ventral portion of pouch 3?

Answer 7

T-cell progenitors from the bone marrow infiltrate the cortex to establish the definitive thymus

Question 8

dorsal portion of pouch 4 forms?

*the ____ cells are are derived from the ____ lining of the pouch

Answer 8

superior parathyroid glands

*the chief (or principle) and oxyphile cells are derived from the endodermal lining of the pouch

Question 9

ventral portion of pouch 4 forms a _______ called the _____ body?

Answer 9

forms a diverticulum called the ultimobranchial body

Question 10

ultimobranchial body releases signaling factors that induce what?
*part of what pouch?

Answer 10

releases signaling factors that induce the migration of neural crest cells into parafollicular (C) cells of the thyroid gland
*pouch 4

Question 11

what is the DiGeorge syndrome?

*leads to hypoplasmia of?

Answer 11

the most common disorder which is caused by the deletion of the long (or “q”) arm of chromosome 22
*hypoplasia of 3 and r pharyngeal pouch derivatives

Question 12

Symptomes of DiGeorge syndrome?

Answer 12

1) thymis hypoplasia (immunodeficiency)
2) hypoparathyroidism (missing or hypoplastic parathyroid glands)
3) outflow tract defects (neural crest in this area also contributes to conotruncal cushions of the outflow tract)

Question 13

anomaly development of the derivatives of pouches 3 and/or 4 can result in?

Answer 13

ectopic or absent parathyroid, thymic, or parafollicular thyroid tissue

Question 14

pharyngeal cleft 1 makes the external?

Answer 14

auditory meatus and ectodermal lining of tympanum

*corresponding 1st pouch develops into auditory tube

Question 15

defects in cleft 1??

Answer 15

result in preauricular (in front of pinna of the ear) cysts and/or fistulas

Question 16

pharyngeal cleft 2,3 and 4 are overgrown by expansion of the __ arch and are usually?

Answer 16

expansion of the SECOND arch and are usually obliterated

really, in the picture, its both arch 2 and 4 growing towards each other

Question 17

remnants of cleft 2, 3. and 4 can appear as?

Answer 17

cervical cysts or fistulas found along the anterior border of the sternocleidomastoid muscle

Question 18

What is the most common cyst?

Answer 18

second bracnhial cleft cyst- tract linked to tonsilar fossa (palatine tonsils)

Question 19

branchial sinus=

Answer 19

blind pouch from pharynx

Question 20

pharyngeal clefts are WHERE in regards to the aortic arch of the same number?

Answer 20

caudal

*note they are both numbered cranially to caudally