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!
GALT is also present in the vermiform appendix, which has what defining characteristics?
- Crypts!!
- NO villi
- Still has simple columnar epithelium with goblet cells
What are the two types of capsulated lymphoid tissues?
Lobules (thymus) and No Lobules (spleen, LN)
The _____ produces only T-lymphocytes, decreases in size with age, replaced by fat and connective tissue, and continues to produce T-lymphocytes in adults
thymus
T and T
Why is the thymus considered a capsulated, lobular tissue?
- 2 lobes with a connective tissue capsule!
- Septa (connective tissue) penetrate to the medulla
- Septa divide thymus into incomplete lobules
The thymus is arranged into a dark outer cortex and light inner ________. Has NO nodules or germinal centers
medulla
Where do T-lymphocytes in the thymus mature?
Cortex
What are the 3 cells in the cortex of the thymus?
- Subcapsular thymic epithelial cells
- Thymic cortical epithelial cells
- Maturing T-cells
The medulla of the thymus is lighter and the site of mature lymphocytes. What else is contained in the medulla? (3)
- Hassal’s corpuscles
- Thymic medullary epithelial cells
- Dendritic cells
TQ: What are contained in both the cortex and medulla of the thymus? (1)
Macrophages
What are hassal’s corpuscles of the thymus and what are their function?
- Only present in medulla
- Closely packed epithelial cells
- Stimulates thymic dendritic cells to complete maturation of T-cells
What is the function of the thymus-blood barrier in the cortex?
-prevent most antigens from reaching developing T-cells
What is being described?
- Capsulated with no lobules
- Located in left superior quadrant
- Macrophages destroy old RBC
- Traps antigens
- Reservoir for 1/3 of platelets
- Hematopoiesis location
Spleen!
What divides the spleen into incomplete compartments?
Trabeculae
What is the difference between red and white pulp of the spleen?
White pulp: rich in lymphoid tissue (clusters)
Red pulp: rich in RBC (b/t white pulp)
(DONT STAIN RED AND WHITE)
____ pulp contains:
- germinal center
- corona
- marginal zone (b/t red and white pulp)
- periarteriolar lymphoid sheath
- central artery
White
___ pulp contains:
- Splenic cord formed by reticular cells
- Splenic sinusoid b/t cords
- Penicillar aa.
- Macrophage sheathed capillaries
- Circulating RBC
Red
Splenic a.--> Trabecular aa.--> Central aa. (surrounded by PALS)--> Radial aa.--> Central aa. leave white pulp--> Penicillar aa. (sheathed by Macrophages)--> Splenic sinusoids (closed) OR Red pulp
What do radial aa. supply?
White pulp marginal zone sinuses
What is being described?
- Smallest, most numerous encapsulated lymphoid organs
- In line filters of lymph
- Removes antigens and cellular debris
- Produces lymphocytes
- Add antibodies
Lymph nodes
What kind of organization do LN have?
- capsule
- Trabeculae
- Outer cortex
- Inner medulla
- Hilum
The outer cortex of the LN has more _-cells and the inner cortex has more _-cells
Outer cortex=B cells
Inner cortex=T cells
What is the medulla arranged into?
cords and sinuses
What are we doing in the sinuses of the LN?
clearing antigens and cellular debris
See hassall’s corpuscles…think?
Thymus
NO nodules
See cortical nodules and sinuses…think?
Lymph nodes
See central arteries…think?
Spleen!
See epithelial coverings…think?
Tonsils!
PB PORE stands for what in ertyhropoiesis? (helps to remember)
- Proerythroblast
- Basophilic Erythroblast
- Polychromatophilic Erythroblast
- Orthochromatic erythroblast
- Reticulocyte
- Erythrocyte
MPM MBM stands for what in granulopoiesis
- Myeloblast
- Promyelocyte
- Myelocyte
- Metamyelocyte
- Band cell
- Mature cell
High numbers of band cells may indicate what?
infection
TQ Monocytes and lymphocytes do not come from the same type of stem cells. What do each come from?
myeloid stem–>monocyte
lymphoid stem cell–>lymphocyte
