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T cells are one of the important types of white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface. T cells are born from hematopoietic stem cells, [1] found in the bone marrow.
Once mature, T cells emigrate from the thymus to provide vital functions in the immune system. [11] [12] Each T cell has a distinct T cell receptor, suited to a specific substance, called an antigen. [12] Most T cell receptors bind to the major histocompatibility complex on cells of the body.
Like invertebrates, plants neither generate antibody or T-cell responses nor possess mobile cells that detect and attack pathogens. In addition, in case of infection, parts of some plants are treated as disposable and replaceable, in ways that few animals can. Walling off or discarding a part of a plant helps stop infection spread. [37]
These cells were named central memory T cells (T CM). They effectively stimulate dendritic cells , and after repeated stimulation they are able to differentiate in CCR7- effector memory T cells. Both populations of these memory cells originate from naive T cells and remain in the body for several years after initial immunization .
Hypersensitive response (HR) is a mechanism used by plants to prevent the spread of infection by microbial pathogens.HR is characterized by the rapid death of cells in the local region surrounding an infection and it serves to restrict the growth and spread of pathogens to other parts of the plant.
The same cells that recognize PAMPs on microbial pathogens may bind to the antigen of a foreign blood cell and recognize it as a pathogen because the antigen is unfamiliar. [11] It is not easy to classify red blood cell recognition as intrinsic or extrinsic, as a foreign cell may be recognized as part of the organism if it has the right antigens.
The cells of meristematic tissue are similar in structure and have a thin and elastic primary cell wall made of cellulose. They are compactly arranged without inter-cellular spaces between them. Each cell contains a dense cytoplasm and a prominent cell nucleus. The dense protoplasm of meristematic cells contains very few vacuoles.
The most advanced tissue culture science is now focused on stem cells, stem cells can be used for tissue replacement or either organs. stem cell is a primitive type of cell which has the ability to differentiate to all the 220 cell types found in human body. Stem cells can be obtained from blood, brain, or muscle tissue but the most important ...