Spleen and Thymus Flashcards
Parenchyma vs Stroma?
Parenchyma – tissue conducts function of organ
Stroma – rest of the tissue (CT, blood, lymph, nerves)
Purpose of a spleen?
removal of old RBC
filter blood (blood-borne antigens)
Components of a spleen?
Capsule (dIRCT)
Trabeculum (dIRCT – carries blood vessels)
Red Pulp = RBC
White Pulp = lymphocytes (intense basophilia)
Blood supply in the spleen?
Trabecular artery –> central artery
– central artery surrounded by PALS (store T cells)
What is the white pulp made of and its blood supply?
radial artery leave central for splenic nodules (B cells)
follicular artery for germinative centre (B cells)
marginal zone – separate splenic nodule + red pulp
What is the red pulp’s blood supply?
capillaires –> closed circulation –> RBC to sinusoid
sheath –> open circulation –> RBC into parenchyma
Sinusoid appearance?
basement membrane form hoops around endothelial cells to allow diffusion of RBC
Purpose of a thymus?
location of T cell development and education
- adults lose T cells = replace with adipose
Components of a thymus?
Capsule (dIRCT)
Trabeculum (dIRCT)
Incomplete Lobules
– Cortex (T cell education) – darker stain
– Medulla
6 Types of epithelioreticular cells?
I – barrier (under capsule)
II – education (cortex)
III – cortex/medulla barrier
IV – medulla/cortex barrier
V – education (medulla)
VI – Hassel’s corpusle formed (medulla)
What junction links epithelial reticular cells?
desmosomes
T Cell Education
CFU-L enter from venule in medulla
travel to cortex and differentiate down toward medulla
1) recognize self-antigens (cortex)
2) recognize foreign antigens (medulla)
MATURE T CELL
Blood supply of thymus?
corticomedullary junction
— trabecular arteriole and veunle span barrier
capillary loops into cortex
Blood-Thymus Barrier?
endothelial cell
basement membrane
pericytes
loose CT with macrophages
basement membrane
type I epithelioreticular cell
