LR01 - Histology of the Lymphatic System One

what two types of tonsils are associated with respiratory epithelium? what two types of tonsiles associated with stratified squamous nonkeratinized epithelium?

Pharyngeal and tubal tonsils •Palatine and lingual tonsils are associated with stratified squamous nonkeratinized epithelium

epithelioreticular cells secrete what things? - 4 things does not secrete what fibers?

epithelioreticular cells secrete thymosin, interferons, interleukins, thymopoietin •Epithelioreticular cells do not secrete any extracellular fibers

diffuse lymphatic tissue what 4 type of cells found? What type of fiber network? •Found in loose CT underneath an epithelial sheet in what 3 tracts? FUNCTION: Diffuse lymphatic tissue recognizes antigens when they do what?

•B-cells, T-cells, plasma cells, APCs in a reticular fiber network •Found in loose CT underneath an epithelial sheet in the GI tract, respiratory tract, and genitourinary tract •Diffuse lymphatic tissue recognizes antigens that have broken through epithelial barriers

Mechanisms to prevent antigens in the thymus they have what type of vessels in the cortex part of the blood-thymus barrier? what 3 other things does it have for a barrier? can lymph filter through the thymus?

•Capillaries located in the cortex are part of the blood-thymus barrier •Continuous capillary •Basal lamina (basement membrane) •Perivascular CT with macrophages •Epithelioreticular cells • lymph does not filter through the thymus

Primary Lymphatic Nodules (Follicles) does it have defined or undefined edges? Dense aggregate of mainly what type of lymphocytes? how are they distributed? - non uniform or uniformed? does it have capsule? loose or dense connective tissue?

•Dense aggregate of mainly inactive B-lymphocytes distributed uniformly throughout the nodule •Defined edges •A part of loose connective tissue but it doesn't have a capsule

appendix what type of lymphatic tissue? what two nodules present here? is there lamina propria?

•Diffuse lymphatic tissue and primary and secondary lymphatic nodules in the lamina propria of the appendix mucosa

tonsils- are partially encapsulated aggregates of what two types of nodules? what type of squamous or epithelium facing the oral cavity? what makes up the capsule - hint its a tissue? Deep invaginations of the epithelium called what?

•Partially encapsulated aggregates of primary and secondary lymphatic nodules •Stratified squamous or respiratory epithelium (E)on the surface facing the oral cavity Connective tissue band on the other side called a capsule called crypts •Pharyngeal tonsils • Tubal tonsils • Palatine tonsils • Lingual tonsil

Peyer's Patches are components of what? associated w what? what two nodules does it contain? is there lamina propria? •Location: what of the small intestine?

•Peyer's patches are a component of gut-associated lymphoid tissue (GALT) Primary and secondary lymphatic nodules in the loose connective tissue (lamina propria) •Location: ileum of the small intestine

Bone Marrow what type of lymphatic organ - primary or secondary? site where lymphocytes become what type of comptent? Red bone marrow is the site of origin of all what type of elements in the blood? REd bone marrow is what type of tissue? found what type of bone? found in what type of skeleton? and what bones?

•Primary lymphatic organs are where lymphocytes become immunocompetent •Red bone marrow is the site of origin of all formed elements in the blood •Red bone marrow is a hematopoietic (blood-forming) tissue found in the spongy bone of most of the axial skeleton and the proximal epiphyses of the humerus and femur

Thymus: Cortex stains how - dark or pale? compared to medulla contains many what cells? these are called what? it has what special cell?

•Stains darkly basophilic with H/E compared to the medulla •Contains a lot of immature T-lymphocytes called thymocytes •Epithelioreticular cells

Thymus: Medulla stains how - dark or pale? compared to cortex? contain what type of cells? - mature or immature t cells? it has what special cell?

•Stains lighter with H/E compared to cortex •Contains mature T-cells that are ready to leave the thymus • Epithelioreticular cells

Thymus is what type of lymphatic organ - primary or secondary? the site of what cell growth and development? what type of connective tissue surronds both lobes? what are the two lobes?

•The thymus is a primary lymphatic organ because it is the site of T-lymphocyte (T-cell) growth, development, maturation, and selection •A dense irregular connective tissue capsule surrounds both lobes •Organized as a cortex and medulla

Thymus: Epithelioreticular Cells only found in thymus how many different types of them are there in the cortex and medulla? FUNCTION??? it is to provide what type of framework for what?

•There are six different types of epithelioreticular cells located throughout the cortex and the medulla •They function to provide a structural framework for the physical and metabolic support of the lymphocytes

Thymus: Hassel's Corpuscles found in cortex or medulla? formed from what type of cell? number what? Hassall's corpuscles synthesize what ? is the function known?

•it's a unique histological feature of the thymus medulla •Formed from epithelioreticular cells type VI Hassall's corpuscles synthesize chemokines •The absolute function of Hassall's corpuscles is currently unclear

Bone Marrow - After production in the red bone marrow most lymphocytes and other immune cells go to secondary lymphoid organs, such as what node and organ? •B-cells differentiate into what type of cells?

•lymphoid organs, such as the lymph nodes and spleen •B-cells differentiate into plasma cells in other organs differentiation into immunocompetent B-cells and primary lymphatic organ

Secondary Lymphatic Nodules (Follicles) its for indication of a type of cell encountering a what? what are the centers here that allow for B-lymphocytes that are differentiating into plasma cells? - how do they stain? these centers have what type of dendrtic cells? what type of cells on the outside?

••Indication that immune cells have encountered and are responding to antigen PALER STAINING: germinal center contains B-lymphocytes that are differentiating into plasma cells •Germinal center has follicular dendritic cells - a type of APC B cells on the out