Non-encapsulated Lymphoid Tissue

Question 1

What are the two main types of nodular lymphoid tissues?

Answer 1

Single nodular and aggregate nodular

Question 2

What are the two categories within single nodular lymphoid tissues?

Answer 2

Primary and Secondary

Question 3

What are the three types of aggregate nodular lymphoid tissues?

Answer 3

The 3 tonsils (Pharyngeal, Palatine, Lingual), Peyer’s patch and Vermiform appendix

Question 4

What is diffuse lymphoid tissue?

Answer 4

Non-encapsulated, diffuse scattering of lymphoid cells deep to epithelium in connective tissue
Strategically located in GI tract, genitourinary tract and respiratory passages

Question 5

What is a primary nodule?

Answer 5

Single nodular tissue

Infrequent, small lymphocytes, prenatal, NO germinal center

Question 6

Secondary nodule:

Answer 6

Single nodular lymphoid tissue, non-encapsulated
More frequent than primary nodule
Germinal center (stains lighter outside, darker inside)
Germinal center possesses clusters of lymphoBLASTS
Memory cells collect in outer ring

Question 7

Tonsils

Answer 7

Partially encapsulated aggregates of lymphoid nodular tissue
Deep to mucosa of nasopharynx, oral cavity and oropharynx
Lymphocytes infiltrate epithelium

Question 8

Pharyngeal Tonsil: What kind of epithelium? Does it have germinal center?
Partial Capsule? Thick or thin?
Location? and how many?

Answer 8

Pseudostratified columnar cliliated epithelium
YES germinal center
YES partial capsule, thin
Posterior of nasopharynx, 1

Question 9

Palatine Tonsil: What kind of epithelium?
Capsule–yes or no? Thickness?
Germinal center?
What is a defining feature of palatine tonsils?
Location and how many?

Answer 9

Stratified squamous epithelium (non-keratinized)
Thick partial connective tissue capsule
YES germinal center
10-15 crypts PER tonsil
Lateral walls of oral cavity, 2

Question 10

Lingual Tonsil: What type of lymphoid tissue?
Epithelium?
Capsule? Thick or thin?
Germinal center?
Defining feature?
Location and how many?

Answer 10

Non-encapsulated, aggregate nodular lymphoid tissue
Stratified squamous
NO capsule
YES germinal center
ONE crypt PER tonsil
Posterior third of tongue, many

Question 11

What are the two main types of non-encapsulated lymphoid tissues?

Answer 11

Diffuse and nodular

Question 12

MALT (Mucosa associated Lymphoid Tissue)

What is it? Where is it found?

Answer 12

Single or clusters of lymphoid nodules
GI tract (Squamous epithelium), Respiratory tract (ciliated pseudostratified columnar), Urinary tract (transitional epithelium)

Question 13

Gut associated Lymphoid tissue:

Where is it found? What is the difference between the two areas that it is found?

Answer 13

Single or clusters of lymphoid nodules found in Ileum (Peyer’s patch) and Vermiform appendix
In Ileum, it has lots of villi, but in appendix, NO villi. But in appendix, lots of crypts
Characterized by simple columnar epithelium with Goblet cells