Thymus gland

Question 1

what type of organ is the thymus gland?

Answer 1

The thymus gland is a pink, lobulated lymphoid organ

Question 2

where is the thymus gland located?

Answer 2

located in the thoracic cavity and neck

Question 3

what is the function of the thymus gland in adolescent?

Answer 3

it is involved the development of the immune system

Question 4

what happens to the thymus gland after puberty?

Answer 4

it decreases in size and is slowly replaced by fat

Question 5

Embryologically, where is the thymus gland is derived from?

Answer 5

the third pharyngeal pouch

Question 6

what type of shape & structure is the thymus gland?

Answer 6

The thymus gland has an asymmetrical flat shape, with a lobular structure

Question 7

what are the lobules comprised of?

Answer 7

The lobules are comprised of a series of follicles, which have a medullary and cortical component

Question 8

where is the cortical portion of the lobules located?

Answer 8

Located peripherally within each follicle

Question 9

what is the cortical portion of the lobules composed of?

Answer 9

It is largely composed of lymphocytes, supported epithelial reticular cells

Question 10

where is the medullary portion of each lobule located?

Answer 10

Located centrally within each follicle

Question 11

What does the medullary portion of each lobule contain?

Answer 11

contains fewer lymphocytes than the cortex, and an increased number of epithelial cells

Question 12

what else is present within the medullary portion of each lobule?

Answer 12

Hassall’s corpuscles are also present

Question 13

what are Hassall’s corpuscles?

Answer 13

these are concentric arrangements of epithelial reticular cells. Their function is unclear

Question 14

where is the thymus gland mainly located?

Answer 14

within the thoracic superior mediastinum, posterior to the manubrium of the sternum

Question 15

where can the thymus gland extend to in some individuals?

Answer 15

it can extend superiorly into the neck (reaching the thyroid gland), and inferiorly into the anterior mediastinum (lying in front of the fibrous pericardium)

Question 16

what is the arterial supply to the thymus gland via?

Answer 16

via the anterior intercostal arteries and small branches from the internal thoracic arteries

Question 17

where does venous blood drains into from the thymus gland?

Answer 17

Venous blood drains into the left brachiocephalic and internal thoracic veins

Question 18

what is DiGeorge syndrome?

Answer 18

a genetic syndrome caused by the deletion of part of chromosome 22. The clinical findings vary greatly between individuals

Question 19

how can the most common features of the syndrome can be memorised?

Answer 19

using the mnemonic ‘CATCH’

Question 20

what does ‘CATCH’ stand for in DiGeorge syndrome?

Answer 20

Congenital heart defects
Abnormal facies
Thymic aplasia
Cleft palate
Hypoparathyroidism

Question 21

what are individuals with an absent or asplastic thymus are susceptible to? why?

Answer 21

recurrent infections due to an underdeveloped immune system