Lymphoid Tissue Part 2 Flashcards
largest lymphoid organ in the body
spleen
immune functions of the spleen (4)
• b-& t-cell replication, manufacture of Ab, Ag removal
• Removes particulate matter & aged or defective rbc’s
from circulation via phagocytosis
• Recycles Fe from Hb
• Hemopoiesis in fetus
removal of spleen
splenectomy
if the spleen is removed, function is taken over by (2)
liver and bone marrow
Dense, fibro-elastic outer capsule contains
smooth Mm cells
mooth Mm cells are important in
splenic contraction in some species
smooth Mm cells act as a reservoir for
rbc’s
Characteristic large, thick bands of dense connective tissue — extend into body of spleen
trabeculae
Characteristic large, thick bands of dense connective tissue — extend into body of spleen
trabeculae
Characteristic large, thick bands of dense connective tissue — extend into body of spleen
trabeculae
Characteristic large, thick bands of dense connective tissue — extend into body of spleen
trabeculae
trabecular contain trabecular (2)
Aa & Vv
Unlike lnn, spleen lacks (2)
cortex & medulla
Bulk of spleen composed of spongy matrix of
red pulp
Within red pulp are (2)
pulp cords & sinusoids
cords of Bilroth
pulp cords
Sinusoids contain mostly
blood
Pulp cords are more —, contain large #’s of (2)
cellular
macrophage and lymphocytes
Pulp cords supported by connective tissue skeleton of (2)
reticular cells & reticular fibers
scattered throughout red pulp are discreet nodules of
white pulp
white pulp contains large #’s of
wbc’s
Areas of white pulp =
follicular areas+/-germinal centers (contain 1’ b-cells), with central A in middle and surrounded by thin, basophilic mantle zone surrounded by paler marginal zone
white pulp functions as a site of (2)
Ag presentation, phagocytosis
white pulp contains large numbers of (3)
macrophages
plasma cells
t helper cells
Splenic nodules
enlarged germinal centers visible to naked
eye
Central Aa surrounded by — rather than b-cells form
t-cells
periarteriolar lymphatic sheaths (PALS)
periarteriolar lymphatic sheaths (PALS) lack — — because
germinal centers, because minimal t-cell proliferation
periarteriolar lymphatic sheaths (PALS) are less — — in humans than other species & require
— — to make positive ID
well developed
immunohistochemical staining
PALS is often used interchangeably with
1’ follicles in white pulp
Branches of splenic A enter white pulp within trabeculae via
trabecular Aa
Branches of splenic A enter white pulp within trabeculae via trabecular Aa, branch & form
central Aa to white pulp
Central Aa continue into red pulp, branch into
perpendicular penicillar Aa
perpendicular penicillar Aa branch into
arterioles
arterioles terminate in
2-3 sheathed capillaries
sheathed capillaries
blind ending capillaries, lack endothelial lining