Immune - lymphatic system

Transcription

1 Immune system - organisation: Immune - lymphatic system - histology & embryology organised lymphoid structures cell components lymphocytes event. lymphatic follicles accessory cells monocytes-macrophages system Immune defense: INNATE IMMUNITY - surface protective system - blood proteins: complement system - phagocytic cells, NK cells ADAPTIVE IMMUNITY - humoral - cell-mediated Immune response: The ability to distinguish self a nonself immune defence x immunodeficiency autotolerance x autoimmune diseases immune supervision x hypersensitivity Lymphoid organs Primary: bone marrow thymus Secondary: spleen (lien) lymph nodes (nodi lymphatici) tonsils diffuse lymphatic tissue in the mucosa of some systems (GALT, BALT) Structure of a lymph node convex face - afferent concave hilum - efferent capsule => trabecule outer cortex inner cortex (paracortical layer) medulla 1

2 Lymph node (HE 8x) Lymph node - capsule (HE 128x) Lymph node - cortex subcapsular sinus intermediate sinuses LYMPHATIC NODULE: ℵ PRIMARY ℵ SECUNDARY: - germinal centre - mantle zone - marginal zone Lymph node - paracortex T- lymphocytes (CD4+) APC (antigen presenting cells) reticular cells high endothelial venules (HEVs) Lymphatic nodule (HE 50x) Lymph node - medulla medullary CORDS B-lymphocytes and plasmocytes APC medullary SINUSES lining of the reticular cells and macrophages reticular fibres over the sinuses=> network 2

3 Lymph node - medulla (HE 20x) Tonsils = accumulated lymphatic tissue under the epithelium without continuous sheath function: lymphocytes production Waldayer`s circle: tonsilla lingualis tonsillae palatinae tonsilla tubaria tonsilla pharyngea Tonsilla palatina (HE 6x) Aggregates of lymphocytes&apc = lymphoid follicles of the same structure as the lymphatic nodules e.g. Peyer`s patches appendix - tonsilla abdominalis Spleen = the largest sec. lymphoid organ (150g) immune filter of the blood erythrocytes destruction Ab production The development of the spleen from 5 th week derived from mesenchym in dorsal mesogastrium mesenchymal cells are differentiated in capsule connective tissue net parenchyma in 4 th month - hematopoesis from 2 nd month - white blood cells forming 3

4 Structure of the spleen CAPSULE of connective tissue: collagen fibres, some smooth muscle cells, elastic fib covered by tunica serosa (except hilum) irradiate connective trabeculae lienalis STROMA composed of reticular fibres RED PULP MARGINAL ZONE WHITE PULP Vascularisation of the spleen aa. trabeculares aa. centrales in PALS = > sinuses of the marginal zone aa. penicillatae => splenic sinusoids - closed circulation => red pulp - open circulation..venae trabeculares, vena lienalis White pulp PALS surrounds the central artery T-lymphocytes germinal centres of the lymphatic nodule B-lymphocytes marginal zone (corona) vascular sinuses a lymphatic tissue APC, B-cells Red pulp splenic sinusoids elongated endothelial cells, incoherent BM surrounded by the reticular fibres cords of Billroth lymphocytes, macrophages, reticular cells, erythrocytes... + reticular tissue Thymus = central lymphoid organ relatively largest in birth (12-14g) after puberty begins to involute some remnants in adult The development of the thymus cortical epithelial cells ectodermal 3th branchial cleft medullary epithelial cells endodermal 3th pharyngeal pouch 10 th week - colonisation by the lymphocytes from the blood islets, the liver and bone marrow maturation of T-cells in immunocompetent cells into lymph nodes, spleen etc. 4

5 The structure of the thymus (HE 15x) capsule trabeculae cortex thymi medulla thymi Cortex of the thymus epithelial cells = star-like cells joined by desmosomes => network many small thymocytes mostly T-lymphocytes many mitosis large T-lymphocytes The medulla of the thymus epithelial cells of endodermic origin thymocytes (small and medial) fully mature T-cells Medulla (HE 480x) Hassall`s corpuscles ( um) The vascularisation of the thymus continuous capillaries functional blood-thymus barrier endothelium & basal lamina pericytes some connective tissue (+ macrophages) epithelial cells in the medulla more developed than in cortex Histophysiology of the thymus T-cells increase carried by the blood into nodes, spleen, Peyer` s patches etc. grow factors production (T-cells proliferation a differentiation) corticoids and steroid hormones attenuate the proliferation, accelerate the involution DiGeorge syndrome - aplasia of the thymus 5