Lymphatics Flashcards
Postcapillary venule location
deep cortex of lymph node
Postcapillary venules
allow lymphocytes to leave blood stream and re-enter lymph node
postcapillary venule endothelium
“high” or tall endothelium
Blood supply of lymph node
enters/leaves at hilus. vessels use trabeculae for distribution & eventually enter parenchyma of node
Pig Lymph nodes
reversal of cortex & medulla
Birds & lymph nodes
birds do NOT have lymph nodes
Hemal Node location
widely distributed in ruminants & pigs
Hemal Node Microscopically
- has nodules throughout, blood, and a capsule.
- does NOT have cortex/medulla, epithelium.
Tonsil types
Palantine, Pharyngeal, Lingual
Palantine & Lingual Tonsil characteristic feature
nonkeratinized stratified squamous epithelium
Pharengeal Tonsil Characteristic Feature
ciliated pseudostratified columnar epithelium
Tonsilar Crypts
- invaginations of epithelium & LP into substance of tonsil
- not ALL tonsils have them
Tonsil Stromal Elements
Capsule (incomplete CCT at base w/o epithelium)
Septa (strands of CCT inwards from capsule, can connect to LP [has reticular ct. and CCT])
Reticular CT in tonils
throughout tonsil as part of stroma
Thymus locations
thoracic to cranial depending on species
Thymus microscopic appearance
- lobules each with cortex & medulla continuous across them
- thymic corpuscles
- capsule
- no lymph nodules
Thymic Corpuscles
- made of degenerating Epithelial-Reticular Cells
- only in medulla
- may aid in t-cell differentiation
Epithelial-reticular cells job
help isolate t-cells from medulla and rest of body
Blood-Thymus Barrier
- located only in cortex
- separates t-cells from blood to protect them from Ag while they’re maturing.
Components of Blood-Thymus Barrier
- Endothelial Cell
- Endothelial Cell Basal Lamina
- Some Ct & macrophages
- Epithelial-Reticular Cell Basal Lamina
- Epithelial-Reticular Cell Cytoplasm
Thymus Funtions
- Development & proliferation of T-cells
- Populates other organs with T-cells
- Humoral Factors made here
Effects of Thymectomy
depends on animal’s age.
-young = compromised adaptive immunity
Thymus does NOT
filter lymph or blood
Spleen
largest lymphoid organ
Spleen’s job
filters blood
Spleen’s microscopic appearance
- lymph nodules throughout, blood in red pulp, contains nodular arterioles.
- NO cortex/medulla, or epithelium
Spleen stroma
Capsule: thick with smooth muscle.
Trabeculae
Reticular CT throughout spleen
White Pulp
- splenic nodules
- B-cells in secondary nodules
- PALS
- nodular arterioles
PALS
Periarterial Sheaths of Lymphocytes
PALS contain
T-cells
PALS do this..
interconnect nodules (b-cells)
Red Pulp
most of parenchyma of spleen
Red Pulp contains.
splenic sinusoids (endothelium) splenic cords
splenic sinusoid
special type of capillary
can’t see them when there’s blood in the spleen
splenic cord
between sinusoids & contains all elements of circulating blood
Spleen’s blood supply
splenic a. -> trabecular aa. -> central aa. -> penicillar aa. ->splenic sinusoids -> pulp vv. -> trabecular vv. -> cranial mesenteric v. -> portal v.
Spleen functions
- early hematocytopoietic
- blood filtration
- blood storage (RBCs & platelets)
- small role in immunity
Cloacal Bursa
in birds only
ID features of Cloacal Bursa
simple columnar or pseudostratified columnar epithelium
smooth mm. on outer wall
Cloacal Bursa Microscopic features
simple columnar or pseudostratified columnar epithelium, LP of CCT, elongated lymph follicles, cortex/medulla per follicle, smooth mm. in outer wall
Cloacal Bursa Function
B-cell proliferation & differentiation site in BIRDS
Peyer’s Patches
aggregations of lymph nodules in lower S.I., cecum, ascending colon
Deep Cortex/Paracortical Zone of Lymph Nodes
contains T-cells & postcapillary venules
where lymphocytes leave blood stream to re-enter lymph nodes
Lymph node medulla’s characteristic arrangement
trabeculae-sinus-cord
Medullary cords
irregular columns of lymphatic tissue separated by lymph sinuses
Lymph node capsule
fibromuscular with CCT & small bit of smooth mm.
General Functions of Lymphatic System
- filtration of lymph/blood
- immunity
What makes up sheathed arterioles in the spleen?
reticular cells & macrophages
What tissue type predominates in sheep/ruminant spleens?
smooth m.
In the thymus, what accounts for the difference in staining affinity between cortex & medulla?
the medulla has lower cell density & has more ER cells present.
the cortex has higher cell density
What is the mammalian functional equivalent to the cloacal bursa?
bone marrow
