Lymph_Histology Flashcards
encapsulated lymphoid tissues
thymus, tonsils, lymph nodes, and spleen
reticular cells
synthesize reticular fibers…type III collagen that makes supporting framework of lymphoid organs
can be phagocytic
diffuse lymphoid tissue
lymphoid tissue that is spread out or not encapsuled
GALT/BALT
Peyers patches
peyers patches location
usually in the ileum
primary lymphoid nodules
no germinal center, mainly resting B cells and dendritic/macros/reticulars
secondary lymphoid nodules
made in response to an antigenic challenge
have germinal center, that is core of resting B cells
mantle or periphery is darker and has plasma cells, resting B cells, memory B cells, dendritic, macro and reticular
lymph nodes functions
maintains and produces B and T cells by clonal expansion
primary location for filtration of lymph
lymph node structures
encapsulates, cortex/medulla, lymphoid nodules, and a hilum
hilum of lymph nodes
region where blood vessels can enter and leave, arterial and venous blood entering and leaving respectively
also has efferent lymphatic vessel for the lymph to leave
lymph node cortex
lymphoid nodules, subscapular and cortical sinuses (sinusoids)
cells in lymphoid nodules
mainly B cells
paracortex of lymph node
mainly T cells that enter in paracortex via high endothelial venules
known as thymus dependent area
contents of medulla of lymph node
medullary sinuses and cords
high endothelial venules
postcapillary venule…made by a simple cuboidal epithelium
where most of lymphocytes leave blood stream and enter the lymph node via diepadesis
typically found in the paracortex of lymph nodes
medullary sinus
endothelium lined spaces, receive lymph from the cortical sinuses
contain macrophages
medullary cords
have lymphocytes and plasma cells
thymus function
maintains T cells, helps T cells mature
thymus structure
encapsulated, has cortex and medulla
epithelial reticular cells of thymus
pale cell that surrounds and extends the outer layer of the thymus… form meshwork within which T cells are tightly packed
synthesize many hormones for making T cells immunocompetent
thymocytes in the thymus
respond to cytokines and become T cells, migrate from cortex to medulla as they mature
surviving T cells are naive and leave thymus to go to secondary lymphoid tissue
blood thymus barrier
within the thymus cortex
makes immunologically protected region ensuring antigens in blood cannot reach the developing T cells in the cortex of the thymus
components of the blood thymus barrier
capillary endothelium and basal lamina
perivascular connective tissue (macrophages)
thymic epithelial reticular cells and basal lamina
medulla of thymus
have the mature T cells that are loosely packed so lighter stained
contains the Hassal Corpuscles
Hassal corpuscles
in thymus medulla, whorl like accretions of epithelial reticular cells
keratinized, increase in number with age
spleen functions
maintains and produces B and T cells through clonal expansion
filters blood
stores RBCs and kills bad ones
prenatla hematopoeisis
structure of spleen
encapsulated with hilum and lymphoid nodules
no cortex or medulla
White pulp nodules in spleen
collections of B cells in the spleen
periarterial lymphatic sheaths
collections of T cells in the white pulp of the spleen
red pulp of spleen
interconnected network of sinusoids and splenic cords
blood flow route in the spleen
splenic artery to trabecular artery to central artert to pnicillar artery to eithe splenic sinusoids of splenic cords
central artery of spleen
artery that runs right through the white pulp of the spleen
penicillar artery of spleen
artery that takes blood from white pulp and into the red pulp of the spleen
sinusoids of the spleen
lined by specialized fusiform epithelial called stave cells
is closed circulation
splenic cords of the spleen
loose connective tissue with plasma, reticular, blood and macrophage cells
open circulation
marginal zone of spleen
where the blood first enters the spleen, space between white and red pulp
has lots of APCs and macrophages
location where T and B cells are sorted into correct spot
tonsil function
maintain and produce B cells
combat antigens entering via nose or oral epithelia
tonsil types
pharygeal, palatine, and lingual tonsils
tonsil structure
encapsulated with lymphoid nodules
no cortex/medulla and no hilum
