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