Histology Flashcards
What are the 2 primary lymphoid organs?
Thymus
Bone Marrow
What the secondary lymphoid organs?
Spleen
Lymph nodes
Tonsils, Adenoids
How do we functionally classify lymphoid tissue?
Primary vs. Secondary Lymphoid Organs
What are the two types of non-encapsulated lymphoid tissue?
Diffuse and Nodular
______ lymphoid tissue simply means that it is scattered. The scattering of lymphoid cells deep to the epithelium in connective tissues such as the GI, GU, and respiratory systems help to create a defense against the outside world.
Diffuse lymphoid tissue
What are the two types of nodular tissue?
Single and aggregate nodular tissue
Single nodular tissue includes what 2 types of tissue?
Primary and secondary nodules
Aggregate nodular tissue include which tissues? (3)
- Tonsils
- Peyer’s Patches
- Vermiform Appendix
What type of single nodular tissue is described?
- Infrequent
- Consists of only small lymphocytes
- Prenatal
- NO germinal center
Primary Nodule of Single Nodular Tissue
What is the defining characteristic in a secondary nodule of single nodular tissue?
Possesses a germinal center!!! (outer ring/cap/mantle and lighter in middle, clusters of lymphoblasts, more frequent than primary nodules)
Where do memory cells collect in a secondary nodule?
In the cap/mantle/outer ring
- Partially encapsulated aggregates of lymphoid nodular tissue
- Deep to mucosa of the nasopharynx, oral cavity, and oropharynx
- Lymphocytes infiltrate the epithelium
Tonsils (aggregate nodular tissue)
Which aggregate tissue is being described?
- Characterized by pseudostratified columnar ciliated epithelium
- Germinal center!
- Thin partial capsule
Pharyngeal tonsil
in an airway!
Which aggregate tissue is being described?
- Characterized by stratified squamous epithelium
- Thick partial connective tissue capsule
- Germinal centers!
- 10-15 epithelial invaginations (Crypts)
Palatine tonsil
(need tough epithelium because food going by)
non-encapsulated! even though has partial capsule
Which aggregate tissue is being described?
- Characterized by stratified squamous epithelium
- NO capsule
- Germinal centers!
- ONE crypt per tonsil !!
Lingual tonsil
What is the difference between palatine and lingual tonsils?
Palatine has many crypts while lingual only has one
Where are peyer’s patches located?
Small intestine in the Ileum
MALT is aggregate nodular tissue associated with mucosa (aka Mucosa-Associated Lymphoid Tissue). It can be single or clusters of lymphoid nodules. Where is it found?
GI, Respiratory, GU systems
If MALT is associated with the Gut then MALT is actually called ____
GALT (Gut-Associated Lymphoid Tissue)
In the Ileum, GALT is called what? What are the 2 big characteristics?
Peyer’s patches! Abundance of villi and goblet cells!