there are two types of organ in immune system. primary or central lymphoid organs and secondary or peripheral lymphoid organs. thymus , bursa of fabricius and bone marrow are the primary lymphoid organs while spleen, lymphnodes and mucosa-associated lymphnoids are the secondary lymphoid organs.
organs and tissues are inter-connected wit blood vessels and tissue lymphatics through which lymphocytes circulate.
1). Primary or Central Lymphoid Organs :- In primary lymphoid organs immature lymphocytes which are generated by haematopoiesis get mature and become committed to a particular antigenic specificity. When it matures in primary lymphoid organ lymphocyte becomes immunocompetent, i.e., capable of mounting an immune response.
I}. Thymus:- Thymus is a greyish, flat, bilobed lymphoid organ situated above heart and extending into the neck on the front and sites of trachea. When it matures it acts as the site of development and maturation of lymphocytes named tymus-derived lymphocytes or T-lymphocytes or T-cells.
Each lobe of Thymus is divided in to a series of lobules,each of which is organized in to two campartments.
1]cortex:outer component
2]medulla:inner component
Cortex is highly dense with thymocytes and medulla is sparsely populated with thymocytes.Thymocytes rapidly divided in the cortex and give rise to T-Lymphocytes.
The T-thymocytes which are produced in thymus only five percent leave the thymus as viable cells and the rest are eliminated due to non productive arrangements and negative selection to eliminate self -reacting T-cells.
Both the cortex and medulla of the thymus contain epithelial cells,dendritic cells and macro phases which contributes the growth and mathuration of thymocytes.
T-limphocytes capable of mounting cell-mediated immune response aganist appropriate antigens.This is effect under the influence of the thymic micro environment and several hormones.The T-lympocytes immediately move from thymus to the secondary or peripheral lympoid organs .
organs and tissues are inter-connected wit blood vessels and tissue lymphatics through which lymphocytes circulate.
1). Primary or Central Lymphoid Organs :- In primary lymphoid organs immature lymphocytes which are generated by haematopoiesis get mature and become committed to a particular antigenic specificity. When it matures in primary lymphoid organ lymphocyte becomes immunocompetent, i.e., capable of mounting an immune response.
I}. Thymus:- Thymus is a greyish, flat, bilobed lymphoid organ situated above heart and extending into the neck on the front and sites of trachea. When it matures it acts as the site of development and maturation of lymphocytes named tymus-derived lymphocytes or T-lymphocytes or T-cells.
Each lobe of Thymus is divided in to a series of lobules,each of which is organized in to two campartments.
1]cortex:outer component
2]medulla:inner component
Cortex is highly dense with thymocytes and medulla is sparsely populated with thymocytes.Thymocytes rapidly divided in the cortex and give rise to T-Lymphocytes.
The T-thymocytes which are produced in thymus only five percent leave the thymus as viable cells and the rest are eliminated due to non productive arrangements and negative selection to eliminate self -reacting T-cells.
Both the cortex and medulla of the thymus contain epithelial cells,dendritic cells and macro phases which contributes the growth and mathuration of thymocytes.
T-limphocytes capable of mounting cell-mediated immune response aganist appropriate antigens.This is effect under the influence of the thymic micro environment and several hormones.The T-lympocytes immediately move from thymus to the secondary or peripheral lympoid organs .
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