Lymphoid Tissue Histology 1

Question 1

Primary lymphoid organs and function

Answer 1

Thymus/bone marrow

Make cell components of immune system

Question 2

Secondary lymphoid organs and function

Answer 2

Tonsils/spleen

Where immune response occurs

Question 3

Non-encapsulated Lymphoid Tissue: Diffuse

Answer 3

• DIFFUSE scattering of lymphoid cells deep to epithelium in connective tissue
• Strategically located in GI tract, genitourinary tract and respiratory passages (to help have a quicker response to the outside world “crap”

Bunch of little lymph cells scattered randomly throughout the connective tissue…not formed into nodes

Question 4

Non-encapsulated Lymphoid Tissue: Single Nodular tissue (primary)

Answer 4

Primary nodules: far more infrequent than Secondary nodules

Consist of only small lymphocytes

Prenatal

Do not possess a germinal center

*No organization

Question 5

Non-encapsulated Lymphoid Tissue: Single Nodular tissue (secondary)

Answer 5

Secondary nodule:

• Far more frequent than primary nodules
• Have germinal center which stains slightly lighter than the outer portion
• Germinal center has clusters of lymphoblasts
• Germinal center and outer ring (mantle zone). Outer has more mature/smaller lymphocytes and inner is more lymphoblasts. Memory cells also collect in outer ring

Question 6

Non-encapsulated Lymphoid Tissue: Aggregate Nodular Tissue- what are the 3?

Answer 6

Tonsils: (3 kinds): Pharyngeal tonsil (adenoids), palatine tonsils, lingual tonsils

-Partially encapsulated aggregates of lymphoid Nodular tissue

• Deep to the mucosa of the nasopharynx, oral cavity and oropharynx
• Lymphocytes infiltrate the epithelium

Question 7

Non-encapsulated Lymphoid Tissue: Aggregate Nodular (Pharyngeal Tonsil)

Answer 7

Pharyngeal Tonsil:

• characterized by pseudo-stratified(often in airway) columnar ciliated epithelium (barrier to outside world). (They all tough the basement membrane). Cilia is present in airways and helps move mucous up. Nasopharynx is also lined in the same way (pseudo-stratified…)
• Does posses a germinal center

Question 8

Non-encapsulated Lymphoid Tissue: Aggregate Nodular Tissue (Palatine Tonsil)

Answer 8

Palatine Tonsil:

• Characterized by *stratified squamous epithelium (need more rigid-protection against tortilla chips)
• Has a thick partial connective tissue capsule
• Has germinal centers
• ***(unique)Has 10-15 epithelial invaginations called Crypts per tonsils

Question 9

Non-encapsulated Lymphoid Tissue: Aggregate Nodular Tissue (Lingual Tonsil):

Answer 9

Lingual Tonsil: (back of tongue)

• Stratified squamous epithelium
• No well defined capsule
• Possesses germinal centers
• Possesses 1 crypt per tonsil

Question 10

Non-encapsulated Lymphoid Tissue: Aggregate Nodular Tissue:

Mucosa-Associated Lymphoid Tissue (MALT)

Answer 10

Mucosa-Associated Lymphoid Tissue (MALT):

Single or clusters of lymphoid nodules

Typically found in GI tract, respiratory passageways and urinary tract

Question 11

Non-encapsulated Lymphoid Tissue:

Mucosa-Associated Lymphoid Tissue (GALT-in GI tract)

Answer 11

Gut-Associated Lymphoid Tissue (GALT):

• GI tract
• In the ileum they are called “Peyer’s patches”
• Characterized by an abundance of villi
• Single or clusters of lymphoid nodules
• *Characterized by simple columnar epithelium with Goblet cells (line the villi)

Question 12

Non-encapsulated Lymphoid Tissue:

Mucosa-Associated Lymphoid Tissue (GALT-in Veriform Appendix)

Answer 12

• Also in Vermiform Appendix (NO villi)
• Characterized by crypts
• Characterized by simple columnar epithelium Goblet cells

Question 13

Villi vs crypts

Answer 13

Villi go up and out

Crypts go down and deep